Page 74 - Start Up Mathematics_1

Addition Shortcuts

Method 1: To add 2-digit numbers, break the number to be added into tens
and ones. Add the tens and ones seperately.

Example: 36 + 20

Solution: 36 + 20 = 30 + 6 + 20

= (30 + 20) + 6

= 50 + 6 = 56
Example: 13 + 27

Solution: 13 + 27 = 10 + 3 + 20 + 7

= (10 + 20) + (3 + 7)

= 30 + 10 = 40
Method 2: Add an easy number close to the actual number and then correct

the answer.
Example: 23 + 47

Solution: 47 is close to 50. (47 + 3 = 50)

So, add 50 to 23.

23 + 50 = 73
Now, correct the answer by subtracting 3 from 73, as we added 3

more than 47.
So, 73 – 3 = 70.

Example: 87 + 96

Solution: 100 is close to 96. (96 + 4 = 100)

So, add 100 to 87.
87 + 100 = 187

Now, correct the answer by subtracting 4 from 187, as we added 4
more than 96.

So, 187 – 4 = 183.

Practise adding these numbers using both methods to see which one you find

easier.

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