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 47
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) Let 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. 48
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 Addition of 2-digit numbers Example 5: Add the following by writing the numbers in columns. 23 + 32 Step 2: Add the tens Solution: Step 1: Add the ones TO TO 23 23 +32 +32 5 5 5 Solve these TO TO TO 41 14 78 +2 8 +3 3 +2 1 Addition 49
Train My Brain Add the following numbers. a) 3 + 7 (Using fingers) b) 6 + 5 (Using a number line) c) 15 + 14 (Using vertical addition) 4.1 I Apply We now know how to add numbers. Let us see some real-life examples of addition of numbers. Example 6: Madhu has 5 kites and Sita has 4 kites. How many kites do they have in all? Solution: Write the numbers one below the other. Add them and write the sum as shown. O 5 +4 9 So, Madhu and Sita have 9 kites in all. Example 7: R am had 14 marbles. Shyam gave him 15 marbles. How many Solution: marbles does Ram have altogether? TO 4.1 Write the numbers one below the other. Add them 14 and write the sum as shown. So, Ram has 29 marbles + 15 altogether. 29 I Explore (H.O.T.S.) We have learnt how to add two 1-digit and 2-digit numbers. Let us now learn to add three 1-digit and 2-digit numbers. 50
Example 8: Sunita bought 2 mangoes, 3 apples and 4 bananas. How many fruits did she buy altogether? Solution: Write the numbers under the ones place and add. O 2 +3 +4 9 So, Sunita bought 9 fruits. Example 9: There are 14 students in Row 1. Row 2 has 15 students. Row 3 has 10 students. How many students are there altogether? Solution: Write the numbers one below the other. Step 1: Add the ones Step 2: Add the tens T O TO 14 14 + 15 + 15 + 10 + 10 9 39 So, there are 39 students altogether. Concept 4.2: Add Two 1-digit Numbers Mentally I Think Bantei had 4 chocolates. His sister gave him 2 more. Bantei could tell the total number of chocolates he has. But he did not use a paper and a pencil. Can you try to find the total mentally? Addition 51
4.2 I Recall To add numbers mentally, first we must know the correct order of numbers. Let us practise the correct order of numbers. Write the numbers in the blanks given. a) 1 to 20 1 ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ 20 ___ ___ ___ ___ ___ ___ ___ b) 33 to 42 33 ___ ___ ___ ___ ___ ___ ___ ___ 42 c) 26 to 45 26 ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ 45 ___ ___ ___ ___ ___ ___ ___ 52
d) 21 to 25 21 ___ ___ ___ 25 4.2 I Remember and Understand To add two numbers mentally, first keep the bigger If the two given number in mind. Then, count the smaller one on numbers are the same, the fingers. we can keep any Let us understand, through these examples. number in mind and count the other number Example 10: Add 2 and 5 mentally on the fingers. Solution: Follow these steps to add mentally: Steps Solved Solve this 2+5 3+6 Step 1: Keep the bigger number in mind. The bigger number is 5. The bigger number is So, keep 5 in mind. ____. So, keep ____ in Step 2: Keep as many The smaller number is mind. fingers open as the 2. So, keep 2 fingers The smaller number is smaller number. open. ____. So, keep ____ fingers Step 3: Begin counting The number after 5 is open. the fingers. Start from the 6. Count 2 fingers as 6 The number after ____ is number after the bigger and 7. number. ____. Count ____ fingers as ____ ,_____ and _____. Step 4: Write the last The sum of 2 and 5 is 7. The sum of 3 and 6 is ___. number as the sum of the given numbers. Addition 53
Example 11: Add 6 and 7 mentally. Solution: Follow the steps to add mentally: Steps Solved Solve this 6+7 5+9 Step 1: Keep the bigger The bigger number is 7. The bigger number is number in your mind. So, keep 7 in mind. ____. So, keep ____ in mind. Step 2: Keep as many The smaller number is The smaller number is fingers open as the 6. So, keep 6 fingers ____. So, keep ___ fingers smaller number. open. open. Step 3: Begin counting The number after 7 is 8. The number after _____ is the fingers. Start from the number after the bigger Count 6 fingers as 8, 9, ____. Count ____ fingers number. 10, 11, 12 and 13. as ____, ____, ____, ____ and ____. Step 4: Write the last The sum of 6 and 7 The sum of 5 and 9 is _________. number as the sum of the is 13. given numbers. Train My Brain Add the following mentally: a) 6 and 5 b) 8 and 9 c) 1 and 4 4.2 I Apply We have seen how easy it is to add two 1-digit numbers mentally. Let us now see a few real life-examples. 54
Example 12: In a class, Team A has 5 students and Team B has 7 students. How many students are there in all? Solution: Number of students in Team A = 5 Number of students in Team B = 7 The bigger number is 7. Keep 7 in the mind. The smaller number is 5. Keep 5 fingers open. After 7, count 5 fingers as 8, 9, 10, 11 and 12. So, the total number of students in the class is 12. Example 13: Seema has 3 milk chocolates and 6 dark chocolates. How many chocolates does she have in all? Solution: Number of milk chocolates = 3 Number of dark chocolates = 6 The bigger number is 6. Keep 6 in the mind. The smaller number is 3. Keep 3 fingers open. After 6, count 3 fingers as 7, 8 and 9. So, Seema has 9 chocolates in all. 4.2 I Explore (H.O.T.S.) We have seen mental addition of two 1-digit numbers. Let us now add three 1-digit numbers mentally. Example 14: Add mentally: 3, 5 and 7 Solution: Follow the steps to add mentally: Steps Solved Solve this 3, 5 and 7 4, 6 and 8 Step 1: Choose the first two numbers. The first two numbers The first two numbers are are 3 and 5. ____ and ____. Addition 55
Steps Solved Solve this 3, 5 and 7 4, 6 and 8 Step 2: Keep the bigger number in mind. The bigger number is 5. The bigger number is So, keep 5 in mind. ____. So, keep ____ in mind. Step 3: Keep as many The smaller number is The smaller number fingers open as the 3. So, keep 3 fingers is _____. So, keep _____ smaller number of the 2 open. fingers open. numbers. Step 4: Begin counting The number after 5 is 6. The number after _____ is the fingers. Count from the number after the Count the 3 fingers as _____. Count the ______ bigger number. 6, 7 and 8. fingers as _____ , _____ , _____ and ______. Step 5: Compare the sum The sum of the first two The sum of the first two of the first two numbers numbers is 8. So, keep numbers is _____. So, with the third number. 8 in mind. Keep the bigger number keep _____ in mind. in mind. Step 6: Keep as many The third number is The third number is ____. fingers open as the third 7. So, keep 7 fingers So, keep ______ fingers number. open. open. 56
Steps Solved Solve this 3, 5 and 7 4, 6 and 8 Step 7: Begin counting the fingers. Count from The number after ______ the number after the sum of the first two The number after 8 is 9. is _____. Count the numbers. Count the 7 fingers as ______ fingers as _____ 9, 10, 11, 12, 13, 14 and , _____ , _____ , _____ , Step 8: Write the last 15. _____ , _____ , _____ , and number as the sum. _____. The sum of 3, 5 and 7 The sum of 4, 6 and 8 is is 15. _____. Example 15: Rahul has 3 apples, 4 chikoos and 6 bananas in his basket. How many fruits does he have in all? Solution: Number of apples in the basket = 3 Number of chikoos in the basket = 4 Number of bananas in the basket = 6 So, the first two are 3 apples and 4 chikoos. The bigger number is 4. Keep 4 in the mind. The smaller number is 3. Open 3 fingers. After 4, count 3 fingers as 5, 6 and 7. So, the sum of the first two numbers is 7. The number of bananas is 6. The bigger number is 7. Keep 7 in the mind. The smaller number is 6. Open 6 fingers. After 7, count 6 fingers as 8, 9, 10, 11, 12 and 13. So, Rahul has 13 fruits in all. Addition 57
Maths Munchies 213 We can add two numbers by drawing lines. 5+3=8 Suppose we have to add 5 and 3. First draw 5 lines and then 3 lines as shown. Then, count the lines continuously. The number we get for the last line is the sum of the two given numbers. 5 + 3 = │││││ + │││ = 8 So, 5 + 3 = 8. Connect the Dots English Fun Some words in the English language are also formed by adding two different words to make a single meaningful word. For example, Moon + light = Moonlight Sun + rays = Sunrays Can you write a few such words? 58
EVS Fun How many fingers do we have in total? To find this we ‘add’ the fingers of both the hands. Can you count the fingers in the given picture? Now, count your own fingers of both hands. Drill Time Concept 4.1: Add 1-digit and 2-digit Numbers 1) Add the following numbers using the Number line. a) 3 and 3 b) 2 and 6 c) 1 and 7 d) 4 and 2 e) 3 and 4 2) Add the following numbers using the vertical or column method. a) 2 and 5 b) 3 and 6 c) 21 and 42 d) 17 and 61 e) 10 and 40 3) Word problems a) I have 2 pens and my sister has 2 pens. What is the total number of pens with us? b) Krish picked 12 sticks and Sanjay picked 20 sticks. How many sticks did they pick in all? Addition 59
Drill Time Concept 4.2: Add Two 1-digit Numbers Mentally 4) Add mentally b) 1 and 3 c) 3 and 3 a) 2 and 7 e) 7 and 9 d) 8 and 2 A Note to Parent Play snakes and ladders with your child to make him or her understand and use addition in a fun and easier way. 60
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