What is the smallest number greater than 100 that is : a)divisible by two ? b)divisible by ten? c)divisible by four ?

I'd start by listing out the multiplies of all three past 100, like this:
102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130
104, 108, 112, 116, 120, 124, 128, 132, 136
110, 120, 130, 140
Now it's just a matter of finding the number that is the same for all three of them, which is 120.

The answer is all about the number 4