Question

If x7y5 is exactly divisible by 3, then the least value of (x + y) is

(a) 6

(b) 0

(c) 4

(d) 3

Answer 1

$\because$ x7y5 is exactly divisible by 3

$\therefore$ Sum of its digits must be divisible by 3

$\therefore$ x + 7 + y + 5 = 12 + (x + y) is divisible by 3

$\therefore$ Least value of x + y = 0 as

12 + 0 = 12 is divisible by 3 (b)