Python/Javascript number precision

Question

Probably this question is already existed somewhere but can't find my specific issue.

I have a two numbers that I want to add and I don't want to use round() function since I am working with money.

1.70 + 1.44 = 3.14 //Returns 3.1399999999999997
1.70 + 1.45 = 3.15 //Returns the correct answer
1.70 + 1.37 = 3.07 //Returns 3.0700000000000003

I tried it in Javascript but still the same issue.

Simple solution: do your calculations in integer by converting to, e.g., dollar to cents. — Sirko, Jul 29 '16 at 09:14
[This](http://floating-point-gui.de/) site might explain why the issue occurs, and how to solve it. — Aurora0001, Jul 29 '16 at 09:14

score 1 · Accepted Answer · answered Jul 29 '16 at 09:19

1

Since you're working with money, always use the decimal.Decimal class in Python.

answered Jul 29 '16 at 09:19

Daniel Roseman

Yeah. I did it like this instead of calculating it in front end. – aldesabido Aug 05 '16 at 06:49

score 0 · Answer 2 · answered Jul 29 '16 at 09:18

0

Use parseFloat to precision :

parseFloat(number).toFixed(precision);

E.g.

parseFloat(1.70 + 1.37).toFixed(2);  // RETURN 3.07

answered Jul 29 '16 at 09:18

Joey Etamity

score 0 · Answer 3 · answered Jul 29 '16 at 09:22

one way you can achieve this is to multiply the values by (10 * precision) that you need and then divide the result by (10 * precision).

you can add a method to do this for you to keep it simple.

3 Answers3