SChand New Learning Composite Mathematics Class 6 Chapter 3 Playing With Numbers Exercise 3D

Exercise 3D

Question 1

(a)12= 5+7

(b) 30= 11+19

(c) 68= 31+37

(d) 72= 31+41

Question 2

(a) 12= 5+7

(b) 30= 13+17

(c) 78= 37+41

(d) 90= 47+53

Question 3

(a) 15 = 3+5+7

(b) 23= 5+7+11

(c) 35= 5+7+23

(d) 55= 13+19+23

Question 4

The five pairs of prime numbers less than 20, whose sum is divisible by 5 —

(2,3) , (3,7), (2,13), (3,17) and (13,17).

Question 5

(a) 151 is divisible by 1 and 151 , so it is a prime number.

(b) 69 is divisible by 1, 3, 2, 69 ,so, it is not a prime number.

(c) 241 is divisible by 1 and 241 so, it is a prime number.

(d) 265 is divisible by 1, 5, 53, 265 so it is not a prime number.

Question 6

The tree prime numbers are 5, 7 and 11

5x7x11= 385

Question 7

F