Apparent F#/BCL floating point bug

Question

The following is in FSI:

> System.Math.Round(0.2916, 2);;
val it : float = 0.29
> it * 100.;;
val it : float = 29.0
> int it;;
val it : int = 28
         


        

Answer 1

This is just how floating point numbers work. The number that appears as 29 in the output is actually slightly smaller than 29 (because floating point numbers are not precise):

> (System.Math.Round(0.2916, 2) * 100.0) - 29.0;;
val it : float = -3.552713679e-15