# Number decimal precision issue. 12+ decimal places added

Hi Bubble Forum,

I have a peculiar issue, after doing regular addition and subtraction operations on a number, the results are sometimes appended with a very small decimal variance. In the region of 0.0000000000001.

For instance, I have record with a number value of 3,132.00, this number is then manually allocated to other sub-records by the user - they split this value at their discretion. In this instance sub-record A got 3,053.70, but sub-record B got 78.3000000000002.

There is no way the user is entering any precision smaller than 2dp. they put a value in an input, and the workflow sets this value for the sub-record.

This is an issue as it breaks my API with the 3rd party accounting system on decimal precision grounds. And yes, I am aware I can use ‘rounded to 2’ on my actions, but as a rule I don’t put them on set workflows using only addition and subtraction operations, as they shouldn’t create such issues?

This is more of a “how the hell is this happening?” post haha. Interested to know if anyone else has seen this and knows what is causing it.

Regards,
Ben
AppyKiwi

Welcome to the world of ‘floating-point arithmetic error’…

You might be forgiven for thinking that computers are incredibly good at maths, and can calculate complex equations to a high degree of accuracy…

But actually, they can’t…

take the classic example of 0.1 + 0.2

Everyone knows that this extremely simply equation equals 0.3

But a computer will give the answer of 0.300000000000000044409

The actual reasons why are quite complex, but put simply it’s because binary (which is a base-2 system), is fundamentally incompatible with decimals (a base-10 system), especially when you have limited resources (which all computers do), which means that certain numbers simply can’t be represented exactly.

Here’s a couple of videos that explain it better than I can, if you’re interested:

Why do computers suck at math? - YouTube

Floating Point Numbers - Computerphile - YouTube