Multiply a Number

How to multiply a number by 10, 100.....?

When we multiply a number by 10, the value of the number increases and the digits of the number move one place to the left on the place value chart.

(a) 24 × 10
2 4 × 1 0 = 2 4 0

(b) 372 × 10
3 7 2 × 1 0 = 3 7 2 0

Similarly, on multiplying by 100, the value of the number increases and the digits of the number move two places to the left on the place value chart.

(a) 36 × 100
3 6 × 1 0 0 = 3 6 0 0

(b) 493 × 100
4 9 3 × 1 0 0 = 4 9 3 0 0

The number of places the digits shift is equal to the number of zeros in the multiplier.
Multiply by 10 — digits shift one place to the left.
Multiply by 100 — digits shift two places to the left.
Multiply by 1000 — digits shift three places to the left.


How to multiply a number by 200, 300 400.....?

(i) 27 × 200
= 27 × 2 × 100
First we multiply the non - zero digits.
27 × 2 = 54
Then we count the number of zeros in both the factors and place them at the end.
27 × 200 = 5400

(ii) 346 × 300
346 × 3 = 1038
There are 2 zeros in the two factors.
Place the zeros at the end.
Answer: 103800

(iii) 240 × 400
24 × 4 = 96
There are 3 zeros in the factors.
(one in 240 and two in 300).
Answer: 96000

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