CO MPASS SERIES mathematics textbook part -1 3 Name: Learn@Home Sec�on: Roll No.: School:
Preface ClassKlap partners with schools, supporting them with learning materials and processes that are all crafted to work together as an interconnected system to drive learning. Our books strive to ensure inclusiveness in terms of gender and diversity in representation, catering to the heterogeneous Indian classroom. ClassKlap presents the Compass series, designed specifically to meet the requirements of the new curriculum released in November 2016 by the Council for the Indian School Certificate Examinations (CISCE). Guiding principles: The 2016 CISCE curriculum states the following as a few of its guiding principles for Mathematics teaching: D evelop mathematical thinking and problem-solving skills and apply these skills to formulate and solve problems. A cquire the necessary mathematical concepts and skills for everyday life and for continuous learning in Mathematics and related disciplines. R ecognise and use connections among mathematical ideas and between Mathematics and other disciplines. R eason logically, communicate mathematically and learn cooperatively and independently. Each of these principles resonates with the spirit in which the ClassKlap textbooks, workbooks and teacher companion books have been designed. The ClassKlap team of pedagogy experts has carried out an intensive mapping exercise to create a framework based on the CISCE curriculum document. Key features of ClassKlap Compass series: Theme-based content that holistically addresses all the learning outcomes specified by the CISCE curriculum. The textbooks and workbooks are structured as per Bloom’s taxonomy to help organise the learning process according to the different levels involved. Student engagement through simple, age-appropriate content with detailed explanation of steps. L earning is supported through visually appealing images, especially for Grades 1 and 2. Increasing difficulty level in sub-questions for every question. Multiplication tables provided as per CISCE requirement. All in all, the Compass Mathematics books aim to develop problem-solving and reasoning skills in the learners’ everyday lives while becoming adept at mathematical skills as appropriate to the primary level. – The Authors
Textbook Features I Will Learn About I Think Contains the list of concepts to be covered Arouses the student’s in the chapter along with the learning curiosity before objectives introducing the concept I Recall I RUenmdeermsbtearndand Pin-Up-Note Recapitulates the E lucidates the basic Highlights the key points or prerequisite knowledge for elements that form the definitions the concept learnt previously basis of the concept ? Train My Brain I Apply I Explore(H.O.T.S.) C hecks for learning to gauge Connects the concept Encourages the child to the understanding level of the to real-life situations by extend the concept learnt student providing an opportunity to more complex scenarios to apply what the student has learnt Maths Munchies Connect the Dots Drill Time Aims at improving speed of Aims at integrating Revises the concepts with calculation and problem Mathematical concepts practice questions at the solving with interesting facts, with other subjects end of the chapter tips or tricks A Note to Parent Engages the parent in the out-of- classroom learning of their child
Contents 1 Shapes 1.1 Understand Spatial Words������������������������������������������������������������� 1 2 Patterns 2.1 Patterns in Our Surroundings������������������������������������������������������� 13 3 Numbers 3.1 Count in Ones and Tens�������������������������������������������������������������� 24 3.2 C ompare 2-digit Numbers���������������������������������������������������������� 34 4 Addition 4.1 Add 1-digit Numbers and 2-digit Numbers������������������������������� 43
Shapes1Chapter I Will Learn About • corners and sides. • basic flat and solid figures. • flat figures as outlines of the surfaces of solid figures. 1.1 Understand Spatial Words I Think Sunny has a glass, a book, a die and a birthday hat. He drew the outlines of their bases. He has three shapes as shown. Do you know what these shapes are called? 1
I Recall Look at the positions of the cat in these pictures. On Under Above Below Near Far 2
In front of Behind Inside Outside Look at the picture given below. The mouse, the cat and the woollen ball are in a line. The mouse is before the cat. The cat is between the mouse and the woollen ball. The woollen ball is after the cat. Shapes 3
Let us recall the concept of position. Choose the correct word to fill the blanks. One is done for you. a) The jug is on the table. (on/in) b) The ball is ___________________ the box. (outside/inside) c) The butterfly is ____________________ the dog. (above/under) d) The cat is ____________________ the table. (above/under) e) The dog is ____________________ the table. (far away from/near) f) The teddy bear is _____________________ the jug. (behind/in front of) I Remember and Understand Figures such as triangle, Let us learn about shapes through an example. square, rectangle and Example 1: Join the dots in order and name the circle are called flat shapes formed. figures. a) b) c) d) 4
Solution: a) Triangle b) Square c) Rectangle d) Circle Let us learn more about flat figures. Study the following table. Flat figure Features Object Corner • 3 sides Side • 3 corners Corner • 4 equal sides Side • 4 corners Corner • 4 sides Side • 4 corners • Opposite sides are equal • No sides • No corners Shapes 5
Example 2: W rite the number of corners of the given figures. One is done for you. Figure Number of corners 3 ? Train My Brain How many sides and corners does each of the following objects have? a) b) c) 6
I Apply Objects such as (cube), (cuboid), (cone) and (sphere) are called solid objects. Their figures drawn using straight or curved lines are called solid figures. Observe the solid figures in the following table. Cube Cuboid Cone Cylinder Sphere Example 3: Some objects are given here. Draw and name the outlines of their bases. Object Outline of the base Circle Triangle Shapes 7
Rectangle Circle Square I Explore (H.O.T.S.) Let us try to identify different solids through an example. Example 4: Observe the given picture and answer the questions that follow. a) H ow many cubes are there? Colour them blue. b) How many cuboids are there? Colour them red. c) H ow many cones are there? Colour them yellow. 8
d) Name the solid figure shown: . Colour them brown. e) How many are there in the given picture? Colour c) 2 d) Cylinder e) 2 them green. Solution: a) 3 b) 4 Maths Munchies Collect 10 things from your home or classroom. Draw the outlines of their bases. Write the names of the objects. Also, write the names of the shapes of their bases. Connect the Dots English Fun Letters such as ‘A’ and ‘V’ of the English alphabet look like triangle. Letters such as ‘O’ and ‘Q’ look like circles. Can you make a rectangle by using the letter ‘L’? What other shapes can you make using the letters of the English alphabet? Shapes 9
EVS Fun Shapes are all around us. What shape do our arms look like? Our arms look like cylinders. What shape do our eyeballs look like? Our eyeballs look like spheres. What shape is the Earth? Drill Time 1.1 Understand Spatial Words 1) Where is the dragon in the given pictures? a ) b) c ) d) e) f) 10
2) Circle the words that tell the position of the cat. One is done for you. h y pmy z d x i c z c j y f l gmh i k x eqbe l own a b o v e wm s x f f ebp t d j g s r e h o y wp z l mo m i nmew j f z n on z pegqc k t ed l unde r do h t r h j ad t a f 3) Name the solid figure that looks like the objects given here. a) b) c) d) Shapes 11
4) Name the shape of the base of these figures. Name the solid figure that looks like these objects. a) b) c) d) A Note to Parent Show your child some objects in your house. For example, television, ball, mobile, wall clock and so on. Ask him or her to identify their shapes. 12
Patterns2Chapter I Will Learn About • simple patterns in shapes and numbers. • patterns from daily life. 2.1 Patterns in Our Surroundings I Think Sunny found paper cuttings of different shapes and sizes. He arranged the pieces in different ways and made many designs. Do you know how a design can be made? I Recall We see many things around us. They all have different sizes, shapes and colours. 13
Recall the flat and solid shapes that we have already learnt. Different shapes are given in this table. Write their names. One is done for you. Figure Name Example Triangle 14
Figure Name Example I Remember and Understand Observe the following pictures. a) b) c) d) From the given pictures, we observe that: Repetition of basic shapes is a) same shapes of different sizes and colours are called a pattern. arranged alternately. b) different shapes of different colours are arranged alternately. Patterns 15
c) s ame shapes of the same size but of two different colours are arranged as a group. d) same shapes of the same size but with multiple colours are arranged as a group. In all these, we observe that the groups repeat many times. Let us see a few examples of patterns. Example 1: Observe the colours of the balloons and complete the pattern. Solution: There are balloons of two colours: pink and purple. They are arranged alternately. So, the pattern formed by these balloons is: Example 2: Complete the following patterns. One is done for you. a) b) c) 16
d) Try th is! Colour the given pictures according to the pattern. a) b) c) ? Train My Brain Complete the following patterns. a) b) c) Patterns 17
I Apply Let us now see some more patterns. Example 3: Tick the picture that comes next in these patterns. One is done for you. Pattern Next picture 18
Example 4: Circle the figure that does not belong to each of the patterns given. One is done for you. a) b) c) d) Patterns can also be seen in numbers as shown. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 I Explore (H.O.T.S.) We see patterns on roofs of buildings and monuments. We also see them on floor tiles, saree borders, dresses, grills and so on. Patterns on floor tiles Patterns 19
Patterns on roofs of monuments Patterns on saree borders Patterns on doors Patterns on grills Example 5: Complete the given patterns. One is done for you. a) 10 20 30 40 50 60 70 20
b) 2 4 6 8 _____ 12 ____ c) 14 13 12 ____ 10 _____ 8 Maths Munchies We see many patterns in our surroundings. Some of them are shown here. Rangoli Mehendi Window grill Beehive Wall Tablecloth Shirt Floor Connect the Dots EVS Fun You know that tigers and zebras have stripes on their bodies. Leopards and giraffes have patches on their bodies. Try to find if there is a pattern in them. Patterns 21
English Fun Poems follow patterns too. Similar sounding words repeat in poems to create rhymes. Here is a short rhyme: Twinkle, twinkle, little star, How I wonder what you are. Up above the world so high, Like a diamond in the sky. Drill Time 2.1 Patterns in Our Surroundings 1) Observe these patterns. Colour the pictures to complete them. a) b) c) d) 2) Observe and complete these patterns: a) _________ _________ _________ 22
b) ________ _________ ________ c) _______ _______ _______ d) _______ _______ ______ 3) Continue the pattern by colouring the correct boxes. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 A Note to Parent Talk to your child about the patterns on floor tiles, wallpapers, clothes and so on in your house. Take a walk around the garden. Help your child to find patterns in nature. For example, the arrangement of branches, leaves and flowers on a tree. Patterns 23
Numbers3Chapter I Will Learn About • the concept of zero. • the sequence of numbers up to 99. • comparing numbers up to 99. 3.1 Count in Ones and Tens I Think Sunny has five sticks. He counted them one by one. His father gave him more sticks to count. Is it easy to count them one by one? Is there an easier way? I Recall We have learnt to count objects and write their numbers. 24
Counting by 1s The numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 are called 1-digit numbers. They are also called single digit numbers. Colour the picture given. Use the colours as given for the numbers. 1 (One) 2 (Two) 3 (Three) 4 (Four) 5 (Five) 6 (Six) 7 (Seven) 8 (Eight) 9 (Nine) Numbers 25
I Remember and Understand There are 5 ducks in a pond. They flew away one by one. At last, there are no ducks in the pond. Let us learn to represent this using a number. Introducing ‘0’ 1 duck flew away. 2 ducks flew away. 4 ducks are in the pond. 3 ducks are in the pond. 3 ducks flew away. 4 ducks flew away. 2 ducks are in the pond. 1 duck is in the pond. All ducks flew away. So, there are ‘zero’ ducks in No ducks are in the pond. the pond. If there are no objects, we write it as zero (0). 26
Example 1: C ount the number of animals. Write the numbers in the boxes. One is done for you. Animals Numbers 4 Counting by 10s Let us say shows 1. Ten such boxes show a 10. So, = 10 ones = 1 ten Counting is easy if we group things into bundles of ten. We can make such collections of 10 with different things. Numbers 27
1 ten of balls 1 ten of books 1 ten of logs Suppose we are given 34 logs of wood to count. First, we count 10 logs and make a bundle. So, one bundle has ten wooden logs. With 34 logs, we can make 3 bundles. 3 tens (written as 30) 4 ones Thus, 4 logs of wood remain. We count these remaining Each digit has its logs in ones. The total number of wooden logs can be place and place written as 3 tens and 4 ones. value in the place value chart. The number 34 has two digits. So, we use Place Value Chart the tens (T) and the ones (O) places for two Places Tens (T) Ones (O) digits. Thus, we write the number 34 in a place value chart as shown. Values 3 4 Abacus counting We can show 2-digit numbers using an abacus. Let us show the number 9 using a spike abacus. 1 shows the number We show a digit in the one. ones place with a blue 9 beads in the ones bead. See Fig. (a). spike show the number 9 blue beads show 9 in nine. the ones place. Each TO TO TO 1 shows the number spike of an abacus can Fig. (a) Fig. (b) ten. have up to 9 beads. 28
See Fig. (b). To show the number 10, we remove all the blue beads. We then put 1 green bead in the tens spike. The tens spike represents the tens place. Let us show the number 34 using a spike abacus. We put 3 green beads in the tens spike. We then put 4 blue beads in the ones spike. In the same way, we can show the numbers 46 and 99 on the abacus. So, 34 is 3 tens and 4 ones, 46 is 4 tens and 6 ones and 99 is 9 tens and 9 ones. TO TO TO Shows 99 Shows 34 Shows 46 Number names Let us now learn the number names from 10 to 99. 10 ― Ten 20 ― Twenty 30 ― Thirty 11 ― Eleven 21 ― Twenty-one 31 ― Thirty-one 12 ― Twelve 22 ― Twenty-two 32 ― Thirty-two 13 ― Thirteen 23 ― Twenty-three 33 ― Thirty-three 14 ― Fourteen 24 ― Twenty-four 34 ― Thirty-four 15 ― Fifteen 25 ― Twenty-five 35 ― Thirty-five 16 ― Sixteen 26 ― Twenty-six 36 ― Thirty-six 17 ― Seventeen 27 ― Twenty-seven 37 ― Thirty-seven 18 ― Eighteen 28 ― Twenty-eight 38 ― Thirty-eight 19 ― Nineteen 29 ― Twenty-nine 39 ― Thirty-nine Numbers 29
40 ― Forty 50 ― Fifty 60 ― Sixty 41 ― Forty-one 51 ― Fifty-one 61 ― Sixty-one 42 ― Forty-two 52 ― Fifty-two 62 ― Sixty-two 43 ― Forty-three 53 ― Fifty-three 63 ― Sixty-three 44 ― Forty-four 54 ― Fifty-four 64 ― Sixty-four 45 ― Forty-five 55 ― Fifty-five 65 ― Sixty-five 46 ― Forty-six 56 ― Fifty-six 66 ― Sixty-six 47 ― Forty-seven 57 ― Fifty-seven 67 ― Sixty-seven 48 ― Forty-eight 58 ― Fifty-eight 68 ― Sixty-eight 49 ― Forty-nine 59 ― Fifty-nine 69 ― Sixty-nine 70 ― Seventy 80 ― Eighty 90 ― Ninety 71 ― Seventy-one 81 ― Eighty-one 91 ― Ninety-one 72 ― Seventy-two 82 ― Eighty-two 92 ― Ninety-two 73 ― Seventy-three 83 ― Eighty-three 93 ― Ninety-three 74 ― Seventy-four 84 ― Eighty-four 94 ― Ninety-four 75 ― Seventy-five 85 ― Eighty-five 95 ― Ninety-five 76 ― Seventy-six 86 ― Eighty-six 96 ― Ninety-six 77 ― Seventy-seven 87 ― Eighty-seven 97 ― Ninety-seven 78 ― Seventy-eight 88 ― Eighty-eight 98 ― Ninety-eight 79 ― Seventy-nine 89 ― Eighty-nine 99 ― Ninety-nine Let us see a few examples. Example 2: Count the number of objects. Write the number and its number name. Solution: The numbers and the number names of the objects are: Objects Number and number name 32 a) Thirty-two 17 b) Seventeen 30
Objects Number and number name 61 c) Sixty-one Example 3: Write the places for each of the given numbers. Then show them on a spike abacus. a) 13 b) 29 c) 64 Solution: Number T O a) 13 1 3 b) 29 2 9 c) 64 6 4 ? Train My Brain TO TO TO c) 64 a) 13 b) 29 Write the number names of the following: a) 1 ten and 4 ones = _______________________ b) 4 tens and 5 ones = _______________________ c) 7 tens and 8 ones = _______________________ I Apply We can form a number when the place values of its digits are given. Let us see a few examples. Example 4: A number has 1 in the tens place and 4 in the ones place. What is the number? Numbers 31
Solution: Write the given digits in the place value chart as shown. So, the number is 14. Example 5: Form numbers using the following: a) 3 in the tens place; 7 in the ones place b) 6 in the tens place; 0 in the ones place Solution: To form the numbers, write the digits in the place value chart as shown. a) T O b) T O 0 3 7 6 So, the numbers are 37 and 60. Example 6: There are four groups for a drama competition. Each group has a few students as shown. Group A Group B Group C Group D 32
a) Count the number of students in Group B. Write its number name. b) C ount the number of students in Group C. Write its Solution: number name. a) There are 10 students in Group B. Its number name is ten. b) T here are 19 students in Group C. Its number name is nineteen. I Explore (H.O.T.S.) Let us see a few examples of 2-digit numbers on an abacus. Example 7: Write the numbers shown on the abacuses. a) b) c) TO TO TO Solution: Count the number of beads T O Number in each spike. Write it in the a) 3 2 32 place value chart. Put a 0 in b) 3 0 30 the places where there are c) 2 3 23 no beads. Example 8: Draw beads on an abacus to show the given numbers. a) 78 b) 25 c) 39 Solution: Write the digits in the place value chart. T O a) 7 8 Draw as many green beads as the tens b) 2 5 digit. Draw as many blue beads as the c) 3 9 ones digit. Numbers 33
a) b) c) TO TO TO 3.2 Compare 2-digit Numbers I Think Sunny has 59 marbles and his brother has 95 marbles. How will they know who has more marbles? I Recall Observe the given picture. It shows cars of different colours. The red car is before The blue car is in The black car is the blue car. between the red after the blue car. and the black cars. The words before, after and between give the positions of a car. In the same way, we can identify the numbers before and after a number. 34
Look at these numbers. 1 2 3 4 5 6 7 8 9 10 11 12 20 19 18 17 16 15 14 13 We see that 4 is before 5 and 5 is after 4. Fill in the blanks with before, between or after numbers. a) _____ is before 14. b) 15 is after _____. c) 7 is between 6 and _____. I Remember and Understand Comparing 2-digit numbers is similar to comparing 1-digit numbers. We can order the numbers after comparing them. Let us learn this concept. Before and after numbers Read the following: a) 11 comes before 12; 12 comes after 11. b) 9 comes before 10 and after 8. So, 9 lies between 8 and 10. c) 15 comes before 16 and after 14. So, 15 lies between 14 and 16. Example 9: Write the before and after numbers of: a) 96 b) 31 c) 49 d) 55 e) 60 Solution: The before number comes before a given number. So, the numbers before the given numbers are: a) 95 b) 30 c) 48 d) 54 e) 59 Numbers 35
The after number comes after a given number. So, the numbers after the given numbers are: a) 97 b) 32 c) 50 d) 56 e) 61 Compare numbers The symbol for greater than is >. We use the concept of more and less to find the The symbol for less greater and the lesser numbers. Observe the than is <. following picture. The symbol for equal to is =. The crocodile’s mouth is open where there are more fish. 4 is more than 1 or 4 is greater than 1. We write it as 4 > 1. The crocodile’s mouth is closed where there are less fish. 2 is less than 3. We write it as 2 < 3. When both the numbers are the same, we say that both are equal to each other. We write as 4 = 4. Let us see a few examples of using the symbols <, > and =. Example 10: Fill in the blanks with the correct symbols (<, > or = ). a) 23 is grea ter than 21. 23 ______ 21 b) 99 is grea ter than 98. 99 ______ 98 36
c) 54 is less than 74. 54 ______ 74 d) 13 is equal to 13. 13 ______ 13 e) 4 is less than 7. Solution: 4 _______ 7 a) 23 > 21 b) 99 > 98 c) 54 < 74 d) 13 = 13 e) 4 < 7 ? Train My Brain Write the numbers that come before and after the given numbers: a) ____, 32, ____ b) _____, 40, ____ c) ____, 25, ____ I Apply Order 2-digit numbers We can compare more than two numbers. For that, we have to arrange them in order. There are two ways to do this: Ascending order: Writing the numbers from the smallest to the largest. Descending order: Writing the numbers from the largest to the smallest. Example 11: Write the numbers 26, 29 and 25 in ascending order. Solution: The given numbers are 26, 29 and 25. Numbers 37
All the three numbers have 2 in their tens place, 2 6, 2 9, 2 5. So, let us compare the digits in their ones place, 2 6, 2 9, 2 5. As 5 < 6 < 9, 25 < 26 < 29. So, the ascending order of the numbers is 25, 26, 29. Example 12: Write the numbers 34, 38 and 30 in descending order. Solution: The given numbers are 34, 38 and 30. All the numbers have 3 in their tens place, 3 4, 3 8, 3 0. So, let us compare the digits in their ones place, 3 4, 3 8, 3 0. As 8 > 4 > 0, 38 > 34 > 30. So, the descending order of the numbers is 38, 34, 30. Form 2-digit numbers Let us learn to form the greatest and the smallest 2-digit numbers. Example 13: Form the greatest and the smallest 2-digit numbers using 2 and 4 (without repeating the digits). Solution: To form the greatest number: TO 42 Write the bigger digit in the tens place and the smaller digit in the ones place. So, the greatest 2-digit number that can be formed is 42. To form the smallest number: Write the smaller digit in the tens place and TO the bigger digit in the ones place. 24 So, the smallest 2-digit number that can be formed is 24. 38
Example 14: Form the greatest and the smallest 2-digit numbers using 5 and 7 (by repeating the digits). Solution: To form the greatest number: TO Find the larger digit. Here, it is 7. 77 Place the same digit in both the places in the place value chart. So, the greatest number is 77. To form the smallest number: TO Find the smaller digit. Here, it is 5. 55 Place the same digit in both the places in the place value chart. So, the smallest number is 55. I Explore (H.O.T.S.) Let us see another example. Example 15: Some children are in a row as shown. Observe the picture and answer the questions that follow. Suma Ravi Rahul Salman Rita Amy a) Which two boys are just after Suma? b) Between which two children is Salman? c) Who is at the right end? Numbers 39
d) Who is just before Rahul? Solution: a) Ravi and Rahul are just after Suma. b) Salman is between Rahul and Rita. c) Amy is at the right end. d) Ravi is before Rahul. Maths Munchies Choose a 2-digit number with a zero in its ones T O Number place. Change the place of its digits. It then becomes a 1-digit number. 3 0 30 For example, take the number 30. If we change the places of its digits, the number becomes 03, 0 3 03 which is the same as 3. Connect the Dots English Fun Arrange the letters D, F, C, J, A, E, G, I, H and B in ascending and descending orders. EVS Fun An adult has 3 tens and 2 ones, that is 32 teeth in his or her mouth. Count the number of teeth you have. How many are they? Write the number of teeth you have in ones and tens. 40
Drill Time 3.1 Count in Ones and Tens 1) Write the numbers in the place value chart. a) 51 b) 90 c) 16 d) 72 e) 39 2) Write the number names of the given numbers. a) 49 b) 31 c) 94 d) 10 e) 32 3) Form numbers which have: a) 4 in the tens place and 1 in the ones place b) 9 in the tens place and 2 in the ones place c) 7 in the tens place and 3 in the ones place d) 8 in the tens place and 6 in the ones place e) 3 in the tens place and 8 in the ones place 3.2 Compare 2-digit Numbers 4) FiIl in the blanks with before, after or between numbers. a) _____ 45 b) 98 _____ c) 19 ______ 21 d) 87 _____ e) ______32 5) Write the symbols >, < or = in the following. a) 34 ____ 30 b) 20 ____ 12 c) 17 ____ 60 d) 84 ____ 84 e) 56 ____ 90 6) Write the greater and the smaller numbers in each of these pairs. a) 39, 19 b) 87, 12 c) 65, 10 d) 45, 41 e) 76, 70 Numbers 41
7) Arrange the numbers in ascending and descending orders. a) 87, 98, 80 b) 19, 17, 30 c) 40, 50, 19 d) 28, 19, 85 e) 34, 10, 99 8) Form the greatest and the smallest 2-digit numbers using the given digits. Do not repeat the digits. a) 3, 2 b) 9, 8 c) 1, 7 d) 4, 6 e) 7, 9 A Note to Parent Ask your child to find the eldest and the youngest members of your family by comparing their ages. Help your child to make a family tree. Place the eldest member on the top and the youngest member at the bottom. 42
Addition4Chapter I Will Learn About • addition of numbers up to 99 without regrouping. • solving day-to-day problems related to the addition of numbers up to 99. 4.1 Add 1-digit Numbers and 2-digit Numbers I Think Sunny can count and add the number of his toys. His father asks him to add 35 and 22. He doesn’t have that many objects to count and add. How can he add these numbers? 43
I Recall Let us recall counting objects using numbers. Look at the vegetables given. Count and write their number in the boxes. Vegetables Number a) b) c) d) I Remember and Understand A pencil stand has 3 pencils as shown in Fig. (a). Another pencil stand has 4 pencils as shown in Fig. (b). Fig. (a) Fig. (b) 44
We count the pencils in the two stands continuously. The last number gives the total number of pencils. Counting the number of objects together is called addition. The answer in addition is called the sum. We use the symbol ‘+’ (read as plus) for addition. Example 1: C ount and write the correct number of objects. One is done for you. a) 1 89 b) c) Addition 45
Methods of addition: The words add, 1) Addition using fingers 2) Addition using the number line total, together, in all, 3) Vertical or column addition altogether and sum are some words used in addition. Let us understand these methods. Addition using fingers Observe these fingers. Each of them shows the number given. Let us learn to add two numbers using fingers. c) 5 and 5 Example 2: Add using fingers: a) 4 and 3 b) 1 and 5 Solution: a) 4 + 3 += 46
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