If is a number with x as its tens digit such that it is divisible by 4. Find all possible values of x.

Question

Philoid · Accepted Answer

Here, given number is divisible by 4

We know that a number is divisible by 4, only when the number formed by its digits in units and tens place is divisible by 4.

∴ x2 is divisible by 4

Expanding x2,

10x + 2 = multiple of 4

Now, x2 can take values 2, 12, 22, 32, 42, 52, 62, 72, 82, 92

Out of these only 12, 32, 52, 72 and 92

∴ x can take values 1,3,5,7 and 9