CBSE Class 6th ( VI) Mathematics Chapter 3. Playing with Numbers :Exercise 3.1

1. Write all the factors of the following numbers :

(a) 24	(b) 15	(c) 21
(d) 27	(e) 12	(f) 20
(g) 18	(h) 23	(i) 36

Answer:

(a) 24	24 = 1 × 24 24 = 2 × 12 24 = 3 × 8 24 = 4 × 6
Thus, the factors of 24 are 1, 2,3, 4, 6, 8, 12 and 24.
(b) 15	15 = 1 × 15 15 = 3 × 5
Thus, the factors of 15 are 1, 3, 5, and 15.
(c) 21	21 = 1 × 21 21 = 3 × 7
Thus, the factors of 21 are 1, 3,7 and 21.
(d) 27	27 = 1 × 27 27 = 3 × 9
Thus, the factors of 27 are 1, 3,9 and 27.
(e) 12	12 = 1 × 12 12 = 2 × 6 12 = 3 × 4
Thus, the factors of 12 are 1, 2, 3, 4, 6 and 12.
(f) 20	20 = 1 × 20 20 = 2 × 10 20 = 4 × 5
Thus, the factors of 20 are 1, 2, 4, 5, 10 and 20.
(g) 18	18 = 1 × 18 18 = 2 × 9 18 = 3 × 6
Thus, the factors of 18 are 1, 2, 3, 6 and 18.
(h) 23	23 = 1 × 23
Thus, the factors of 23 are 1 and 20.
(h) 36	36 = 1 × 36 36 = 2 × 18 36 = 3 × 12 36 = 4 × 9 36 = 6 × 6
Thus, the factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36

2. Write first five multiples of :

(a) 5

(b) 8

(c) 9

Solution :

(a) 5	5 × 1 = 5 5 × 2 = 10 5 × 3 = 15 5 × 4 = 20 5 × 5 = 25
Thus, The required first five multiples of 5 are 5, 10, 15, 20 and 25.
(b) 8	8 × 1 = 8 8 × 2 = 16 8 × 3 = 24 8 × 4 = 32 8 × 5 = 40
Thus, The required first five multiples of 5 are 8, 16, 24, 32 and 40.
(c) 9	9 × 1 = 9 9 × 2 = 18 9 × 3 = 27 9 × 4 = 36 9 × 5 = 45
Thus, The required first five multiples of 5 are 9, 18, 27, 36 and 45.

3. Match the items in column 1 with the items in column 2.

Column 1	Column 2
35 15 16 20 25	Multiple of  8 Multiple of  7 Multiple of  70 Factor of  30 Factor of  50 Factor of  20

Answer:

Column 1	Column 2
35 15 16 20 25	(b) Multiple of  7 (d) Factor of  30 (a) Multiple of  8 (f) Factor of  20 (e) Factor of  50