1. Subtraction Subtraction is a process of taking away Look at the examples: 2 – 1 = 1 2Take away 1 Leaves 1

2. 4 -2 = 2 4take away 2 leaves 2

3. 7 – 4 = 3 7 take away 4 leaves 3

4. The Sign – indicates subtraction. It is read as minus sign. We read 5 – 3= 2 as five minus three is equal to two. 5 – 3 = 2 is called a subtraction fact. In 5 – 3 = 2, 2 is called the difference of 5 and 3.

5. Fill in the boxes 6 – 2 = 3 – 1 =

6. Using counters, find the difference: 7 - 3 8 -3 5 - 1 5 -4 8 - 6 9 - 3

7. Properties of Subtraction 4take away 0 leaves 4 3take away 0 leaves 3

8. What do we observe? We see that when 0 is subtracted from a number, the number remains the same. Again observe the following: 3 – 3 = 0 1 – 1 = 0

9. Fill in the boxes 1. 4 – 0 =6. 5 - = 0 2. 12 – 0 =7. 15 - = 15 3. 3 - = 38. - 2 = 0 4. 9 - = 99. 9 – 0 = 5. - 0 = 710. - 11 = 0

10. More about subtraction 4 tens – 2 tens = 2 tens 40 - 20 = 20 7 tens – 3 tens = 4 tens 70 – 30 = 40

11. What do we observe ? We see that when we subtract 10, 20, 30 etc, from 40,50, 60 e.t.c, we subtract tens only. Then we put a zero to the right of the difference obtained above. For example, 60 – 20 = There are 6 tens. 2 tens are taken away. 6 – 2 = 4 So we have 60 – 20 = 40.

12. Fill in the boxes: 1.40 – 10 = 2. 50 – 30 = 3. 70 – 20 = 4. 60 – 30= 5. 90 – 40 = 6. 30 – 20 = 7. 60 – 50 = 8. 80 – 10 = 9. 70 – 60 = 10. 90 – 30 = 11. 70 – 30 = 12. 50 – 20 =

13. More about subtraction Observe the following: 4 tens – 2 tens = 2 tens 40 – 20 = 20 7 tens – 3 tens = 4 tens 70 – 30 = 40

14. What do we observe? We see that when we subtract 10,20,30 e.t.c from 40, 50,60 e.t.c, we subtract tens only. Then we put a zero to the right of the difference obtained above. For example, 60 – 20 = There are 6 tens. 2 tens are taken away. 6 – 2 = 4 So, we have 60 – 20 = 40.

15. Fill in the boxes 1.40 – 10 = 2.50 – 30 = 3.70 – 20 = 4.60 – 30 = 5. 90 – 40 = 6. 30 – 20 = 7. 60 - 50 = 8.80 – 10 = 9. 70 – 16 = 10. 90 – 30 = 11.70 – 3- = 12.50 – 20 =

16. Observe the following 54 – 30 = 2442 – 30 = 12

17. What we observe? We see that when we subtract 10 or 20 or 30 etc., from a number we take away tens only. There is no change in ones. For example, 76 – 20 = There are 7 tens. 2 tens are taken away. Thus, 7 – 2= 5 tens are left over and there is no change in ones. So, we have 76 – 20 = 56.

18. Fill in the boxes 1.51 – 20 = 2.66-30 = 3.87 – 40 = 4.93 – 50 = 5. 63 – 60 = 6. 89 – 40 = 7. 71 – 50 = 8. 82 – 60 = 9. 84 – 30 = 10. 63 – 20 = 11. 74 – 10 = 12. 57 – 40 =

19. Subtraction without Regrouping ( or without Borrowing) Subtract 23 from 44: Expanded form : 44 4 tens + 4 ones - 23 2 tens + 3 ones 2 tens + 1 one so, 44 – 23 = 2 tens + 1 one = 21

20. Short Form: Step 1. Arrange the given numbers in columns.Write the greater number above the smaller number. Step 2. Subtract the digits in ones column. Step 3. Subtract the digits in tens column. T O 4 4 - 23 T O 44 - 23 1 T O 4 4 - 23 2 1

21. Subtract 1. 93 - 52 2.45 - 24 3. 99 - 87 4. 45 - 34

22. Regrouping of Numbers from Tens to ones 1 ten + 3 ones = 13 ones

23. 2 tens + 4 ones= 1 tens + 14 ones

24. In the same way, we have 1. 6 tens + 5 ones = 5 tens + 15 ones 2. 4 tens + 9 ones = 3 tens + 19 ones 3. 8 tens + 0 ones = 7 tens + 10 ones

25. Fill in the boxes: 1. 2 tens + 4 ones = ten + 14 ones 2. 3 tens + 2 ones = 2 tens + ones 3. 8 tens + 3 ones= tens + 13 ones 4. 7 tens + 4 ones = 6 tens + ones 5. 9 tens + 0 ones= 8 tens + ones 6. 5 tens + 6 ones = tens + 16 ones

26. Subtraction with Regrouping (or with Borrowing) Subtract 16 from 34. Write the numbers under T and O columns. Leave a gap just below T and O. T O Method 2 14 step 1: 4 ones – 6 ones is not possible. 3 4 Regroup 3 tens as 2 tens + 1 ten= 2 tens+ - 1 6 10 ones. 1 8 Now 10 ones + 4 ones= 14 ones. 14 ones – 6 ones = 8 ones. Write 8 in the ones place of the answer. Step 2: 2 tens – 1 ten = 1 ten.

27. Subtract the following: T O 3 5 - 1 8 T O 3 6 - 1 7 T O 3 7 - 1 9 T O 4 3 - 1 5 T O 8 4 - 2 5 T O 8 5 - 3 7 T O 9 4 - 4 3 T O 7 5 - 2 6

28. Addition and Subtraction Find : 10 + 5 – 3 Step 1: First add 10 and 5 1 0 step 2: subtract 3 from 15 + 5 1 5 1 5 10 - 3 or +5 12 15

29. Find 25 -7+ 14 step 1 1 15 2 5 - 7 1 1 8 18 +14 32 Hence, 25 – 7 + 14= 32