# Ncert Class 6 Math Playing With Numbers Exercise 3.1

Playing With Numbers Class 6 Ex. 3.1

Ncert Class 6 Math Free Solution.

Exercise 3.1

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

Solution 1:-
(a) Factors of 24 are:
24 = 1 x 24;
24 = 2 x 12;
24 = 3 x 8;
24 = 4 x 6

So, all the factors of 24 are :-  1, 2, 3, 4, 6, 8, 12 and 24.

(b) Factors of 15 are:
15 = 1 x 15;
15 = 3 x 5
So, all the factors of 15 are :-  1, 3, 5 and 15.

(c) Factors of 21 are:
21 = 1 x 21;
21 = 3 x 7
So,  all the factors of 21 are :-  1, 3, 7 and 21.

(d) Factors of 27 are:
27 = 1 x 27;
27 = 3 x 9.
So,  all the factors of 27 are :-   1, 3, 9 and 27.

(e) Factors of 12 are:
12 = 1 x 12;
12 = 2 x 6;
12 = 3 x 4
So,  all the factors of 12 are :-   1, 2, 3, 4, 6 and 12.

(f) Factors of 20 are:
20 = 1 x 20;
20 = 2 x 10;
20 = 4 x 5
So,  all the factors of 20 are :-   1, 2, 4, 5, 10 and 20.

(g) Factors of 18 are:
18 = 1 x 18;
18 = 2 x 9;
18 = 3 x 6;
So, all the factors of 18 are :-  1, 2, 3, 6, 9 and 18.

(h) Factors of 23 are:
23 = 1 x 23;
So,  all the factors of prime number 23 are :-  1 and 23.

(i) Factors of 36 are:
36 = 1 x 36;
36 = 2 x 18;
36 = 3 x 12;
36 = 4 x 9;
36 = 6 x 6;
So,  all the factors of 36 are :- 1, 2, 3, 4, 6, 9, 12, 18 and 36.

Question 2 :- Write first five multiples of :-
(a) 5        (b) 8          (c) 9

Solution:
(a) First five multiples of 5 are:
5 x 1 = 5;
5 x 2 = 10;
5 x 3 = 15;
5 x 4 = 20;
5 x 5 = 25;
So,  the required multiples of 5 are :-  5, 10, 15, 20 and 25.

(b) First five multiples of 8 are:
8 x 1 = 8;
8 x 2 = 16;
8 x 3 = 24;
8×4 = 32;
8 x 5 = 40;
So,  the required multiples of 8 are :-  8, 16, 24, 32 and 40.

(c) First five multiples of 9 are:
9 x 1 = 9;
9 x 2 = 18;
9 x 3 = 27;
9 x 4 = 36;
9 x 5 = 45;
So,  the required multiples of 9 are :-  9,18, 27, 36 and 45.

Question 3 :- Match the items in column I with the items in column II.

Column 1                          Column 2

(i) 35                                  (a)  Multiple of 8
(ii) 15                                 (b) Multiple of 7
(iii) 16                                (c) Multiple of 70
(iv)  20                               (d)  Factor of 30
(v)  25                                (e) Factor of 50
(f) Factor of 20

Solution 3:-
(i)  →  (b)      {because, 7 x 5 = 35}
(ii) →  (d)      {because, 15 x 2 = 30}
(iii) → (a)      {because,  8 x 2 = 16}
(iv) → (f)       {because,  20 x 1 = 20}
(v) →  (e)      {because,  25 x 2 = 50}

Question 4 :- Find all the multiples of 9 upto 100.
Solution 4:-
9 x 1 = 9;
9 x 2 = 18;
9 x 3 = 27;
9 x 4 = 36;
9 x 5 = 45;
9 x 6 = 54;
9 x 7 = 63;
9 x 8 = 72;
9 x 9 = 81;
9 x 10 = 90;
9 x 11 = 99;
So,  all the multiples of 9 upto 100 are :-

9, 18, 27, 36, 45, 54, 63, 72, 81, 90 and 99.