#2 Bad round

[Anonymous]

Hello,
I have a problem with decimal number.

I insert the decimal number: 3.172
but when I extract it the number appear like 3.1719999.

Could you explain this?
How I can solve the problem.

At the level of apllication I can put a "round", but is it
possible sove the problem at the level of library?

Thank you a lot.