202110764-TRAVELLER_PREMIUM-STUDENT-TEXTBOOK-MATHEMATICS-G01-Combine

MATHEMATICS TEXTBOOK – Grade 1 Name: _________________________ Section: ________Roll No: _______ School: ________________________

Contents Part 1 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

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 a) 13 b) 29 c) 64 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 = _______________________ Numbers 31

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

Solution: c) 54 is less than 74. 54 ______ 74 d) 13 is equal to 13. 13 ______ 13 e) 4 is less than 7. 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, ____ Numbers 37

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

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. 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. Addition 47

To 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 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 48

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 55 5 TO Solve these TO 41 78 +2 8 TO +2 1 14 +3 3 ? Train My Brain Add the following: a) 3 + 7 (Using fingers) b) 6 + 5 (Using a number line) c) 15 +14 (Using vertical addition) Addition 49

Contents Part 2 6 Subtraction 6.1 Subtract 1-digit Numbers and 2-digit Numbers .......................13

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