Question

if 793x 0 is a multiple of 3 where x is a digit what is the value of x

Answer 1

as sum of digits of any number if divisible by 3.then 3 is a multiple of it.
so 7+9+3+x+0=19so the nearest number which is divisible by 3 is 21
so we have to add 2 to the number.
so the value of x is 2

Answer 2

If a number must be divisible by 3 then the sum of digits of the number must be divisible by 3

As x varies between 1 to 9

So that by the given is
793x0 = 7+9+3+x+0
19+x= divisible by 3
So that the numbers be (2,5,8)
..proof..
7+9+3+2+0=21. ..21 is divisible by 3
7+9+3+5+0=24. ..24 is divisible by 3
7+9+3+8+0=27. ..27 is divisible by 3

...hence solved...