Page 41 - Math Skill - 4

Multiplication and Division 39

2. The product of three numbers does not change, when we group them differently. For
example,

(6 × 13) × 4 = 78 × 4 = 312 and 6 × (13 × 4) = 6 × 52 = 312

Hence, (6 × 13) × 4 = 6 × (13 × 4)
3. The product of a number and 1 is the number itself. For example,

63 × 1 = 63, 981 × 1 = 981, 2434 × 1 = 2434
4. The product of a number and 0 is always 0. For example,

6 × 0 = 0, 173 × 0 = 0, 91478 × 0 = 0

5. Multiplication of a given number by 10, 100 and 1000:
(a) To multiply a given number by 10, add one zero to the right of the given number.
For example,
35 × 10 = 350, 951 × 10 = 9510, 6834 × 10 = 68340

(b) To multiply a given number by 100, add two zeroes to the right of the given number.
For example,
68 × 100 = 6800, 498 × 100 = 49800, 7312 × 100 = 731200

(c) To multiply a given number by 1000, add three zeroes to the right of the given number.
For example,
58 × 1000 = 58000, 697 × 1000 = 697000, 5137 × 1000 = 5137000

Exercise 3.2

1. Fill in the blanks.
(a) 628 × ______ = 628 (b) ______ × 1 = 930

(c) 4381 × ______ = 0 (d) 563 × ______ = 32 × 563
(e) 0 × 8347 = ______ (f) 9840 × ______ = 0

2. Fill in the blanks.
(a) 93 × 10 = ______ (b) 874 × 100 = ______ (c) 683 × 10 = ______

(d) 1507 × 100 = ______ (e) 934 × 1000 = ______ (f) 473 × 1000 = ______
(g) 19 × 10 = ______ (h) 347 × 100 = ______ (i) 3967 × 1000 = ______

3. Find the products.
(a) 63 × 10 (b) 79 × 20 (c) 832 × 600
(d) 198 × 200 (e) 62 × 300 (f) 48 × 400

4. Add.
(a) 67 to itself 10 times. (b) 378 to itself 100 times.

(c) 278 to itself 1000 times.