Page 92 - Start Up Mathematics_1

Subtraction Shortcuts

Method 1: To subtract 2-digit numbers, break the number to be subtracted into
tens and ones. Subtract in parts.

Example: 76 – 45

Solution: 76 – 45 = 76 – 40 – 5
= (76 – 40) – 5

= 36 – 5 = 31

Example: 97 – 28
Solution: 97 – 28 = (97 – 20) – 8

= 77 – 8 = 69
Method 2: Instead of subtracting, find the number to be added to the smaller

number to get the bigger number.
Example: 91 – 88

Solution: 88 + 3 = 91 Note: This method works if

So, 91 – 88 = 3. the two numbers are close to
Example: 659 – 653 each other.

Solution: 653 + 6 = 659
So, 659 – 653 = 6.

Method 3: Subtract an easy number close to the actual number and then correct
the answer.

Example: 73 – 38

Solution: Subtract 40 (38 + 2) from 73, as it is close to 38 and easy to subtract.
73 – 40 = 33

Now, correct the answer by adding 2 to 33, as we subtracted 2 more
than 38.

So, 73 – 38 = 35.
Example: 110 – 93

Solution: Subtract 90 (93 – 3) from 110, as it is close to 93 and easy to subtract.

110 – 90 = 20
Now, correct the answer by subtracting 3 from 20, as we subtracted 3
less than 93.

So, 110 – 93 = 17.

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