Why do binary arithmetic operations sometimes result in different outputs?

[megaflop]

Hello everyone !
I got a problem, I can't figure out why when I compute $A+B$ and $2\times (\frac{A}{2}+\frac{B}{2})$ the result is sometimes different.
Can anyone explain why the results of the two operations are different ?

Edit : A and B are coded in binary of course and we compute a binary addition.

 

[jim hardy]

Are you using integer or floating point ?

My guess is former , and one of the numerators is an odd number.

 

[megaflop]

Integers I forgot to mention sorry.

 

[jim hardy]

Well there you go.

Got Basic?

FOR I = 1 , 10 , 1
PRINT I, INT( I/2)
NEXT I
END

 

[megaflop]

Well there you go.

Got Basic?

FOR I = 1 , 10 , 1
PRINT I, INT( I/2)
NEXT I
END

I see thank you :) .

 

[uart]

Integers I forgot to mention sorry.

Does only "misbehave" if you're using one or more odd integers?