Question

If the 4-digit number x27y is exactly divisible by 9, then the least value of (x + y) is 

A. 0 

B. 3 

C. 6 

D. 9

Answer 1

We know that if sum of digits of a number is divisible by 9, then the number is divisible by 9. 

Here, 

x + 2 + 7 + y = multiple of 9 

x + y + 9= 0, 9, 18, … 

Hence, 

x + y + 9 = 9 

∴ x + y =0 

But x + y cannot be 0 because then x and y both will have to be 0.Since x is the first digit, it cannot be 0.∴ x + y + 9 = 18 x + y = 9 

∴ the least value of (x + y) is 9