The sum of positive and negative numbers does not equal zero.

[Nico67543]

Hi all, 

The sum of these two number isn't equal to 0. It equal to 4.07453626394272E-10, why was that happened?

 

  

[alexnajm]

Your data must have some underlying decimal places! You can use a Round function to get it to 0 - something like Round([External]+[SE26],0.01)

[caltang]

That's how precise it gets. Your decimal places are quite precise - I would recommend to do your formula first, then at the end, use the Multi-Field tool to change the data type to fixed decimal, 19.0 to get it down if it helps. 

If you round and do your formulas, you may end up with E.C.F. - error carried forward.

[apathetichell]

A double is a number stored as a fraction. On larger numbers (with decimals) it can be quite dififcult to get standard addition/subtraction to equal to 0. I'd recmmend swapping to fixed decimal 19.6.