Subtraction
Subtraction is the process of taking away some objects from a collection and counting the remaining objects in the collection
The sign of subtraction is - (minus)
Properties of Subtraction
| Property | Definition | Example |
|---|---|---|
| Subtracting 0 | When we subtract 0 from a number, the difference is the number itself. | 5 - 0 = 5 4 - 0 = 4 |
| Subtracting same number | When we subtract a number from itself, the difference is 0. | 5 - 5 = 0 8 - 8 = 0 |
| Subtracting 1 | When we subtract 1 from a number, the difference is just before number. | 5 - 1 = 4 8 - 1 = 7 |
Subtracting by Regrouping
Subtraction is not possible when the first number is smaller than the second number
(i) Subtracting a 1-digit number from a 2-digit number
Let's find 34 - 8Step 1:
Write the numbers like below.
3 4
- 8
- 8
Step 2:
There are not enough ones, so we will regroup the tens.3 tens = 2 tens + 1 tens
3 tens = 2 tens + 10 ones
2 10
3 4
- 8
3 4
- 8
Step 3:
Now the numbers are easy to subtract.10 - 4 = 6, write 6 in ones place
2 - 0 = 2, write 2 in tens place.
2 10
3 4
- 8
2 6
34 - 8 = 263 4
- 8
2 6
(ii) Subtracting a 2-digit number from another 2-digit number
Let's find 35 - 17Step 1:
Write the numbers like below.
3 5
- 1 7
- 1 7
Step 2:
There are not enough ones, so we will regroup the tens.3 tens = 2 tens + 1 tens
3 tens = 2 tens + 10 ones
Now we have 10 + 5 = 15 ones
2 15
3 5
- 1 7
3 5
- 1 7
Step 3:
Now the numbers are easy to subtract.15 - 7 = 8, write 8 in ones place
2 - 1 = 1, write 1 in tens place.
2 15
3 5
- 1 7
1 8
35 - 17 = 183 5
- 1 7
1 8
Think and Answer
64 - 25 = ______?
56 - 38 = ______?
30 - 14 = ______?
53 - 27 = ______?
50 - 8 = ______?
42 - 28 = ______?
39
18
16
26
42
14
Linking Addition and Subtraction
Consider the following addition and subtraction facts.
6
+ 5
11
+ 5
11
5
+ 6
11
+ 6
11
11
- 5
6
11- 5
6
- 6
5
When we subtract one of the numbers from the sum, we will get the other number.
The three numbers in an addition or subtraction fact make a NUMBER FAMILY
Also, we can verify the process of subtraction by adding the smaller number to the difference, the sum should be the bigger number.
Also, we can verify the process of subtraction by adding the smaller number to the difference, the sum should be the bigger number.