questions about fractions

[stapper]

hi,

I have 2 questions
1)
I give JD a value off : 2436116.31
If I print JD it gives the correct value
but if i print the fraction it gives : .310000000055879354

2)
If i give F the value of the fraction of JD
I expected it wil be .31
but it is .310000000055879354
if i do math with than i have a problem

How can i avoid this ?

kind regards