In integer arithmetic:

2*125/100 == 2

In floating point arithmetic:

2*125/100 == 2.5

I think I'll stick with the floating point!

If you want to work with fractions, try rotating all the numbers left n-bits. Then the rightmost n-bits of the numbers effectively become a fraction added to the number (remember that multiplying by 2 is equivalent to rotating left 1 bit).

(2*2^8) * (125*2^8) / (125*2^8) = 640

Your answer, in binary is 0000 0010 1000 0000.
That is interpretted as 2 + 128/256 = 2.5

- Lee