Floating point error in representation?

Question

when i make this multiplication

0.94 * 8700

the output is

8177.999999999999

but i

Answer 1

It isn't an error. IEEE floats can't represent decimal numbers exactly.

Answer 2

The specific reason in your case is that the real number 0.94 cannot be represented exactly in a double precision floating point. When you type 0.94, the actual number stored is 0.939999999999999946709294817992486059665679931640625.