Page 69 - Revised Maths Wisdom Class - 3

Multi plicati on 67

Let's Practise

14 × 5 = ________ 16 × 8 = ________ 13 × 9 = ________

12 × 7 = ________ 11 × 9 = ________ 15 × 8 = ________

Multiplication by 10, 100 and 1000

When multiplying by 10: When multiplying by 100: When multiplying by 1000:
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add one zero to the right of add two zeroes to the right of add three zeroes to the right of
the number. the number. the number.

53 × 10 = 53 tens 29 × 100 = 29 hundreds 8 × 1000 = 8 thousands
= 530 = 2900 = 8000

47 × 10 = 47 tens 64 × 100 = 64 hundreds 7 × 1000 = 7 thousands
= 470 = 6400 = 7000

83 × 10 = 83 tens 49 × 100 = 49 hundreds 2 × 1000 = 2 thousands

= 830 = 4900 = 2000

Some more tricks

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13 × 20 4 × 300
= 13 × 2 × 10 = 4 × 3 × 100  If you want to do the multiply by
9 then fi rst multiply the number

= 26 × 10 = 260 = 12 × 100 = 1200 by 10 aft er that subtract the
number from the product.
3 × 2000 3 × 3000

= 3 × 2 × 1000 = 3 × 3 × 1000 For example:
= 6 × 1000 = 6000 = 9 × 1000 = 9000 25 × 9 = 25 × 10 –25 = 250 – 25 = 225

Exercise 5D

1 Multiply.

(a) 64 × 10 = ______ (b) 35 × 10 = ______ (c) 53 × 10 = ______

(d) 193 × 10 = ______ (e) 274 × 10 = ______ (f) 333 × 10 = ______

(g) 717 × 10 = ______ (h) 812 × 10 = ______ (i) 432 × 10 = ______