MAGNOLIA-STUDENT-TEXTBOOK-MATHEMATICS-G01-Combine

MATHEMATICS TEXTBOOK 1 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Contents 1Class Part 1 3 Numbers 3.1 Count in Ones and Tens ................................................................................. 22 3.2 Compare 2-digit Numbers ............................................................................. 31 4 Addition 4.1 Add 1-digit and 2-digit Numbers ................................................................... 38

Chapter Numbers 3 Let Us Learn About • the concept of zero. • the sequence of numbers up to 99. • place value and face value of numbers. • writing number names. • comparing, ordering and forming numbers. Concept 3.1: Count in Ones and Tens Think Bantei 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? Recall We have learnt to count objects and write their numbers. 22

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 23

& Remembering and Understanding 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 the No ducks are in the pond. pond. 24 If there are no objects, we write it as zero (0).

Example 1: Count 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. 1 ten of balls 1 ten of books 1 ten of logs Numbers 25

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 logs in ones. The total number of wooden logs can be written as 3 tens and 4 ones. The number 34 has two digits. So, we use the Place Value Chart tens (T) and the ones (O) places for two digits. Thus, we write the number 34 in a place value Places Tens (T) Ones (O) chart as shown. Values 3 4 Each digit has its place and place value in the place value chart. Abacus counting We can show 2-digit numbers using an abacus. Let us show the number 9 using a spike abacus. TO TO TO One shows the We show a digit in the number 1. ones place with a blue bead. See Fig. (a). Nine in the ones spike show the 9 blue beads show 9 in number 9. the ones place. Each spike of an abacus can One shows the have only 9 beads. number 10. Fig. (a) Fig. (b) 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. 26

TO TO TO shows 34 shows 46 shows 99 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 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 Numbers 27

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 61 c) Sixty-one 28

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 TO TO TO a) 13 b) 29 c) 64 Numbers 29

Concept 3.2: Compare 2-digit Numbers Think Bantei has 59 marbles and his sister has 95 marbles. How will they know who has more marbles? Numbers 31

Recall Observe the given picture. It shows cars of different colours. The red car is before The blue car is The black car is the blue car. between the red and after the blue car. 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. Look at these numbers. We see that 4 is before 5 and 5 is after 4. 1 2 3 4 5 6 7 8 9 10 11 12 20 19 18 17 16 15 14 13 Fill in the blanks with before, between or after numbers. a) _____ is before 14. b) 15 is after _____. c) 7 is between 6 and _____. & Remembering and Understanding Comparing 2-digit numbers is similar to comparing 1-digit numbers. We can order the numbers after comparing them. Let us learn this concept. 32

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) 1 5 comes before 16 and after 14. So, 15 lies between 14 and 16. Example 9: Write the numbers that come before and after: a) 96 b) 31 c) 49 d) 55 e) 60 Solution: The numbers before and after the given numbers are: Number Before Number After Number 96 95 97 31 30 32 49 48 50 55 54 56 60 59 61 Compare numbers We use the concept of more and less to find the greater and the lesser numbers. The symbols for greater than, less than and equal to are is >, < and =. Observe the following picture. The crocodile’s mouth is open The crocodile’s mouth is closed where there are more fish. where there are less fish. 4 is more than 1 or 4 is greater than 1. 2 is less than 3. We write it as 4 > 1. 2 is smaller than 3 We write it as 2 < 3. Numbers 33

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 ______ 21 b) 99 ______ 98 c) 54 ______ 74 d) 13 ______ 13 e) 4 _______ 7 Solution: a) > b) > c) < d) = e) < 34

Chapter Addition 4 Let Us Learn About • adding numbers up to 99 without regrouping. • adding two 1-digit numbers mentally. • different methods of adding numbers. Concept 4.1: Add 1-digit and 2-digit Numbers Think Bantei can count and add the number of his toys. His father asks him to add 35 and 22. He does not have that many objects to count and add. How can he add these numbers? 38

Recall Let us recall counting of objects. Look at the vegetables given. Count and write their numbers in the boxes. Vegetables Number a) b) c) d) e) Addition 39

& Remembering and Understanding A pencil stand has 3 pencils as shown in Fig. (a). Another pencil stand has 4 pencils as shown in Fig. (b). We count the pencils in the two stands continuously. The Fig. (a) Fig. (b) 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. The words add, total, together, in all, altogether and sum are some words used in addition. 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) 40

c) Methods of addition: 1) Addition using fingers 2) Addition using the number line 3) Vertical or column addition Let us understand these methods. Addition using finger Observe these fingers. Each of them shows the number given. Addition 41

Let us learn to add two numbers using fingers. Example 2: Add using fingers: a) 4 and 3 b) 1 and 5 c) 5 and 5 Solution: a) 4 + 3 += Open 4 fingers on one hand. Open 3 fingers on the other. B egin counting the fingers on one hand. Continue to count the fingers on the other hand. The number counted for the last finger is the sum or total. So, 4 + 3 = 7. b) 1 + 5 += So, 1 + 5 = 6. c) 5 + 5 += So, 5 + 5 = 10. Addition using the number line A line marked with numbers is called the number line. We use it to add numbers. Let us see an example. 42

Example 3: Add using the number line: a) 2 and 3 b) 4 and 4 c) 3 and 4 Solution: a) L et us find 2 + 3 using the number line. Draw an arrow from 0 to 2. T o add 3 to 2, we move 3 steps to the right of 2. Draw arrows for each step as shown. The number at which the steps end is 5. So, 2 + 3 = 5. b) 4 + 4 So, 4 + 4 = 8. c) 3 + 4 So, 3 + 4 = 7. Vertical or column addition We can add numbers by writing them one below the other. This is called vertical addition or column addition. Let us see a few examples. Addition 43

Addition of 1-digit numbers Example 4: Add 6 and 2 by writing the numbers in columns. Solution: Write the numbers under the ones place, as shown. O 6 +2 8 Addition of 2-digit numbers Example 5: Add the following by writing the numbers in columns. 23 + 32 Solution: Step 1: Add the ones Step 2: Add the tens TO TO 23 23 +32 +32 5 55 TO Solve these TO 41 78 +2 8 TO +2 1 14 +3 3 44

Contents 1Class Part 2 5 Subtraction 5.1 Subtract 1-digit and 2-digit Numbers ��������������������������������������������������������������1

Chapter Subtraction 5 Let Us Learn About • different methods of subtracting numbers. • subtracting numbers up to 99 without regrouping. Concept 5.1: Subtract 1-digit and 2-digit Numbers Think Bantei has 44 toffees. He gave 11 toffees to his sister. Bantei wants to know how many toffees remain with him. How do you think Bantei can find that? Recall Look at the vegetables given. A few of the vegetables are cut in each question. Find the remaining number of vegetables. Vegetables Number a) 1

Vegetables Number b) c) d) & Remembering and Understanding There are 5 animals in a farm. 3 of them went away. We now count the number of animals left in the farm. 2

This count gives the remaining number of animals in the farm. Counting the number of objects remaining or leftover is called subtraction. The answer we get on subtracting is called the difference. Subtract, left, remain and difference are some words used in subtraction. We use the symbol ‘−’ (read as minus) for subtraction. Example 1: Count and write the correct number of people/objects. One is done for you. a) 5 32 b) Subtraction 3

c) Methods of subtraction: 1) Subtraction using fingers 2) Subtraction using the number line 3) Vertical or column subtraction Let us understand these methods. Subtraction using fingers We have already learnt to show numbers using our fingers. Let us learn to subtract one number from the other using fingers. 4

Example 2: Subtract using fingers. Solution: a) 2 from 6 b) 3 from 5 c) 7 from 9 a) S ubtracting 2 from 6 O pen 6 fingers on the two hands. Close two fingers. C ount the open fingers on the hands. They are 4 in number. So, the difference of the given numbers is 4. That is, 6 – 2 = 4. b) 5 – 3 Open 5 fingers. Close 3 fingers. Count the open fingers. They are 2 in number. So, 5 – 3 = 2. c) 9 – 7 Open 9 fingers on the two hands. Close 7 fingers. Count the open fingers. So, 9 – 7 = 2. Subtraction using the number line A line marked with numbers is called a number line. We can use the number line to subtract numbers. Let us see an example. Example 3: Solve using the number line: a) 5 – 3 b) 6 – 1 c) 7 – 4 Solution: a) T o find 5 – 3 using the number line, we start from 5. Subtraction 5

D raw an arrow from 0 to 5 as shown. This shows the first number. 5 T hen, move 3 steps to the left. Draw arrows for each step as shown. 5 The number at which we end the steps is 2. So, 5 – 3 = 2. b)  6 6 So, 6 – 1 = 5. 7 c) 7  So, 7 – 4 = 3. 6

Vertical or column subtraction We can subtract by writing the smaller number below the bigger one. This is called vertical subtraction or column subtraction. Let us see a few examples. Subtraction of 1-digit numbers Example 4: Subtract 5 from 9 by writing the numbers in columns. Solution: Write the given numbers under the ones place, as shown. o 9 –5 4 Subtraction of 2-digit numbers Example 5: Subtract 32 from 75 by writing the numbers in columns. Solution: Follow the steps to subtract. Step 1: Subtract the ones Step 2: Subtract the tens T O TO 75 75 –3 2 –3 2 3 43 TO Solve these TO 84 47 –4 1 TO –2 3 87 –4 2 Subtraction 7