Page 35 - Start Up Mathematics_5

Example 17: Find the following products.
Working
(a) 7,645 × 10 (b) 9,037 × 30 1 2 1 2
(b) 9 0 3 7 (c) 2 1 3 1 6
(c) 21,316 × 40 (d) 5,38,210 × 60
× 3 × 4
Solution: (a) 7,645 × 1 0 = 76,45 0 2 7 1 1 1 8 5 2 6 4
↓ ↓
4 1
number followed by 0 (d) 2 5 3 8 2 1 0
(b) 9,037 × 3 0 = 2,71,110 × 6

(c) 21,316 × 4 0 = 8,52,640 3 2 2 9 2 6 0

(d) 5,38,210 × 6 0 = 3,22,92,600

Multiplication by 100 and its multiples

• To multiply a number by 100, write the number followed by two zeros.

• To multiply a number by any multiple of 100, write two zeros at the end and then multiply
the number by the remaining digit(s) and write
the product before the two zeros.
Working
Example 18: Find the following products. 1 1 3 5 1
(b) 2 4 3 1 5 (c) 3 1 5 9 2 1
(a) 6,849 × 100 (b) 24,315 × 300
× 3 × 6
(c) 3,15,921 × 600 (d) 70,416 × 500
7 2 9 4 5 1 8 9 5 5 2 6
Solution: (a) 6,849 × 1 00 = 6,84,900
2 3
(b) 24,315 × 3 00 = 72,94,500 (d) 7 0 4 1 6
× 5
(c) 3,15,921 × 6 00 = 18,95,52,600
3 5 2 0 8 0
(d) 70,416 × 5 00 = 3,52,08,000

Mental Maths

Find the product.
(a) 78,564 × 100 (b) 9,12,306 × 100
(c) 21,311 × 200 (d) 12,121 × 900

Multiplication by 1,000 and its multiples

• To multiply a number by 1,000, write the number followed by three zeros.
• To multiply a number by any multiple of 1000, write three zeros at the end and then
multiply the number by the remaining digit(s) and write the product before the three
zeros.

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