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# Mental Arithmetic: add and subtract multiples of 10 and 100 mentally

Mental Arithmetic : Able to add and subtract multiples of 10 and 100 mentally.

Mental Arithmetic

Able to add and subtract multiples of 10 and 100 mentally.

Multiples of 10 and 100 are useful in counting large number of items and objects (including money).

Multiples of 10

10, 20, 30, 40, 50....

Here, one’s place didn’t change, when they are added to zero and hundreds Place also didn’t change, only the tens place got changed.

i) 2 + 1 = 3

ii) 4 + 1 = 5

EXAMPLE 1

4 + 0 = 4

7 + 1 = 8

Therefore 374 + 10 = 384

EXAMPLE 2

8 + 3 = 11

Here, 11 has two digits, in this keep 1 in the tens place, take the other 1 and add with the hundreds place digit.

Therefore 286 + 30 = 316

Here, one's place and ten's place didn't change, when they are added to zero but in the hundreds place it is changed.

EXAMPLE 3

2 + 0 = 2

8 + 0 = 8

6 + 1 = 7

682 + 100 = 782

EXAMPLE 4

8 + 1 = 9

835 + 100 = 935

Subtracting by multiples of 10

EXAMPLE 5

Subtract 10 from 625

5 – 0 = 5

2 – 1 = 1

625 – 10 = 615

EXAMPLE 6

Subtract 50 from 981

8 – 5 = 3

981 – 50 = 931

Subtracting by multiples of 100

EXAMPLE 7

Subtract 400 from 546

5 – 4 = 1

546 – 400 = 146

Tags : Numbers | Term 3 Chapter 2 | 4th Maths , 4th Maths : Term 3 Unit 2 : Numbers
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4th Maths : Term 3 Unit 2 : Numbers : Mental Arithmetic: add and subtract multiples of 10 and 100 mentally | Numbers | Term 3 Chapter 2 | 4th Maths