Question

If 7x8 is exactly divisible by 9, then the least value of x is

(a) 0

(b) 2

(c) 3

(d) 5

Answer 1

$\because$ 7x8 is exactly divisible by 9

$\therefore$ Sum of its digits must be divisible by 9

$\Rightarrow$ 7 + x + 8 = 15 + x must be divisible by 9

$\therefore$ Least value of x = 3 as 15 + 3 = 18 is divisible by 9.