Android Question Math accuracy problems

[JLS]

Hi everybody:

As my very first Project, I'm creating a calculator.

I have found for example:

0.3 * 3 = 0.89999999999999

Why is this happening? How can it be fixed?

Thanks in advance

 

[sorex]

it's because the way how computers work with floating numbers.

you'll have to apply some rounding.

 

[klaus]

To display numbers you should use NumberFormat or NumberFormat2.

 

[JLS]

I suspected something like that.

Thank you all for answer so fast.

 

[keirS]

To display numbers you should use NumberFormat or NumberFormat2.

To do calculations that require decimal precision you should not use floating point calculations. agrahm's BigNumbers library is the answer to this problem. It's not a display issue it's calculation issue.

 

[klaus]

In most cases BigNumber calculations are not necessaray, Double calculations are enough.
But the display is anoying, therefore the suggestion to use NumberFormat.