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
`Related Concept
● Addition
● Check for Subtraction and Addition
● Word Problems Involving Addition and Subtraction
● Estimating Sums and Differences
● Multiply a Number by a 2Digit Number
● Multiplication of a Number by a 3Digit Number
● Word Problems on Multiplication
● Division of TwoDigit by a OneDigit Numbers
● Division of FourDigit by a OneDigit Numbers
● Division by 10 and 100 and 1000
● Division by TwoDigit Numbers
4th Grade Math Activities
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