Playing with Numbers - Solutions

 CBSE Class –VI Mathematics

NCERT Solutions
Chaper 3 Playing With Numbers (Ex. 3.1)

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Question 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 = 1 x 24 = 2 x 12 = 3 x 8 = 4 x 6 = 6 x 4
∴$\therefore$ Factors of 24 = 1, 2, 3, 4, 6, 12, 24

(b) 15 = 1 x 15 = 3 x 5 = 5 x 3
∴$\therefore$ Factors of 15 = 1, 3, 5, 15

(c) 21 = 1 x 21 = 3 x 7 = 7 x 3
∴$\therefore$ Factors of 21 = 1, 3, 7, 21

(d) 27 = 1 x 27 = 3 x 9 = 9 x 3
∴$\therefore$ Factors of 27 = 1, 3, 9, 27

(e) 12 = 1 x 12 = 2 x 6 = 3 x 4 = 4 x 3
∴$\therefore$ Factors of 12 = 1, 2, 3, 4, 6, 12

(f) 20 = 1 x 20 = 2 x 10 = 4 x 5 = 5 x 4
∴$\therefore$ Factors of 20 = 1, 2, 4, 5, 10, 20

(g) 18 = 1 x 18 = 2 x 9 = 3 x 6
∴$\therefore$ Factors of 18 = 1, 2, 3, 6, 9, 18

(h) 23 = 1 x 23
∴$\therefore$ Factors of 23 = 1, 23

(i) 36 = 1 x 36 = 2 x 18 = 3 x 12 = 4 x 9 = 6 x 6
∴$\therefore$ Factors of 36 = 1, 2, 3, 4, 6, 9, 12, 18, 36

Question 2. Write first five multiples of:
(a) 5, (b) 8, (c) 9
Answer: (a) 5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
∴$\therefore$ First five multiples of 5 are 5, 10, 15, 20, 25.
(b) 8 x 1 = 8
8 x 2 = 16
8 x 3 = 24
8 x 4 = 32
8 x 5 = 40
∴$\therefore$ First five multiples of 8 are 8, 16, 24, 32, 40.
(c) 9 x 1 = 9
9 x 2 = 18
9 x 3 = ,27
9 x 4 = 36
9 x 5 = 45
∴$\therefore$ First five multiples of 9 are 9, 18, 27, 36, 45.

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

Column 1	Column 2
(i) 35	(a) Multiple of 8
(ii) 15	(b) Multiple of 7
(iii) 16	(c) Multiple of 70
(iv) 420	(d) Factor of 30
(v) 10	(e) Factor of 50

Answer: (i) →$\to$ (b), (ii) →$\to$ (d), (iii) →$\to$ (a), (iv) →$\to$ (c), (v) →$\to$ (e)

Question 4. Find all the multiples of 9 up to 100.
Answer: Multiples of 9 up to 100 are:
9, 18, 27, 36, 45, 54, 63, 72, 81, 90, 99