Rails 3 Float Rounding Error

Question

Running ruby 1.8.7.

(1.005 * 100).round result: 100

(1.006 * 100).round result: 101

100.5.round result: 101

(1.005 * 100) result: 100.5

What is going on here? Can someone try this in the latest version of ruby please? Thanks!

Answer 1

Floating Point Math is what's going on.

For the last one, I do not get 100.5, and you aren't either, even if for some reason it's displaying as that:

Loading development environment (Rails 3.2.8)
1.9.3p194 :001 > (1.005 * 100).round
 => 100 
1.9.3p194 :002 > (1.006 * 100).round
 => 101 
1.9.3p194 :003 > 100.5.round
 => 101 
1.9.3p194 :004 > (1.005 * 100)
 => 100.49999999999999