# NCERT Solutions for Class 6 Maths Chapter 3 Exercise 3.4

NCERT Solutions for Class 6 Maths Chapter 3: NCERT Solutions for Class 6 Maths Chapter 3 Playing With Numbers Exercise 3.4

## NCERT Solutions for Class 6 Maths Chapter 3 Whole Numbers Exercise 3.4

1. Find the common factors of:
(A) 20 and 28
(B) 15 and 25
(C) 35 and 50
(D) 56 and 120

Solution:

(A) Factors of 20=1,2,4,5,10,20
Factors of 28=1,2,4,7,14,28
Common factors =1,2,4

(B) Factors of 15=1,3,5,15
Factors of 25=1,5,25
Common factors =1,5

(C) Factors of 35=1,5,7,35
Factors of 50=1,2,5,10,25,50
Common factors =1,5

(D) Factors of 56=1,2,4,7,8,14,28,56
Factors of 120=1,2,3,4,5,6,8,10,12,15,20,24,30,40,60,120
Common factors =1,2,4,8

2. Find the common factors of:
(A) 4, 8 and 12
(B) 5, 15 and 25

Solution:

(A) 4,8,12
Factors of 4=1,2,4
Factors of 8=1,2,4,8
Factors of 12=1,2,3,4,6,12
Common factors =1,2,4

(B) 5,15, and 25
Factors of 5=1,5
Factors of 15=1,3,5,15
Factors of 25=1,5,25
Common factors =1,5

3. Find the first three common multiples of:
(A) 6 and 8
(B) 12 and 18

Solution:

(A) 6 and 8

Multiple of 6=6,12,18,24,30
Multiple of 8=8,16,24,32
3 common multiples =24,48,72

(B) 12 and 18

Multiples of 12=12,24,36,78
Multiples of 18=18,36,54,72
3 common multiples = 36,72,108

4. Write all the numbers less than 100 which are common multiples of 3 and 4.

Solution:

Multiples of 3=3,6,9,12,15…
Multiples of 4=4,8,12,16,20…
Common multiples =12,24,36,48,60,72,84,96

5. Which of the following numbers are co-prime?
(A) 18 and 35
(B) 15 and 37
(C) 30 and 415
(D) 17 and 68
(E) 216 and 215
(F) 81 and 16

Solution:

(A) Factors of 18=1,2,3,6,9,18
Factors of 35=1,5,7,35
Common factor =1
Therefore, the given two numbers are co-prime

(B) Factors of 15=1,3,5,15
Factors of 37=1,37Common factors =1
Therefore, the given two numbers are co-prime.

(C) Factors of 30=1,2,3,5,6,10,15,30
Factors of 415=1,5,83,415
Common factors =1,5
As these numbers have a common factor other than 1, the given two numbers are not co-prime.

(D) Factors of 17=1,17
Factors of 68=1,2,4,17,34,68
Common factors =1,17
As these numbers have a common factor other than 1, the given two numbers are not co-prime.

(E) Factors of 216=1,2,3,4,6,8,9,12,18,24,27,36,54,72,108,216
Factors of 215=1,5,43,215
Common factors =1
Therefore, the given two numbers are co-prime.

(F) Factors of 81=1,3,9,27,81
Factors of 16=1,2,4,8,16
Common factors =1
Therefore, the given two numbers are co-prime 