Question

determine whether the first number is divisible by the second number 120;3 (yes or no)

Answer 1

Yes.

Here's a trick that works with 'divisible by 3' :

-- Take the original number . . . . . 120

-- Add up its digits . . . . . . 1 + 2 + 0  =  3

-- If the sum of the digits is divisible by 3, then the big number is too.

                                   3 is divisible by 3, so 120 is too.