What is the smallest number which when increased by 3 is divisible by and 21 ?

Correct option is D

Solution:

So we first need the LCM of these numbers.

27 = 3³

35 = 5 × 7

25 = 5²

21 = 3 × 7

the LCM is;

= 3^3​ × 5² × 7

= 27 × 25 × 7 = 4725

The smallest no which when increased by 3 is 27, 35, 25 & 21 = 4725 - 3

= 4722