irb(main):001:0> 0.1 * 3 => 0.30000000000000004A lot of Ruby developers fall back to using integers and only fixing it when displaying the result.
However, this only works well if you have indeed have fixed decimal points.
If not, you have to use
rationals. Which isn't too bad, except there was no nice syntax for
them (short of changing the return value of
Ruby 2.1 introduces the
suffix for decimal/rational literals to fix this:
irb(main):001:0> 0.1r => (1/10) irb(main):002:0> 0.1r * 3 => (3/10)
Casiano Rodriguez León 2015-06-18