Question : Subtracting 2 Numbers Problem

I am trying to subtract 2 numbers; the numbers come from different sources (one from the Internet, the other from a table in a database where its type is decimal.

If they both have the same value, when I try to subtract them, I get a result like 7.105427357601e-015. I tried casting to int (.to_i) and it works fine but I lose the decimal part.  If I cast them to float I get a similar result to that given above.  I cannoy think of any other cast to make.

Another thing if the two numbers are 84.21 and 80.21, the difference is 3.9999999999999

Subtracting 84.21 from 80.18 produces the correct value.

Sometimes I despair.

Can anyone help?

Answer : Subtracting 2 Numbers Problem

Yep, I spotted the error
please look at my last comment