JavaScript calculations are inaccurate with decimal numbers with more than 16 digits

[Angelin_faith (Angelin faith Sheeba)]

Hi Mozilla Community,

I just tried decimal calculations in JavaScript and C# and noticed that the JavaScript calculations are inaccurate for numbers with 17 or more digits. But it is accurate in C#. Take a look at the examples and screenshots for reference. Here’s my question: Is it possible to calculate decimal numbers in JavaScript with the same accuracy as in C#?

Sample: https://stackblitz.com/edit/js-ulm42k?file=index.js,index.html

Screenshot:
Javascript

C#

[jwhitlock (John Whitlock)]

Hi Angelin_faith! This is a known issue with floating-point math (math with numbers with a decimal point) in just about every programming language. For more information:

• https://0.30000000000000004.com - a one-page explainer with code examples.
• https://wizardzines.com/zines/integers-floats/ - an illustrated guide to computer math, released 2023
• https://floating-point-gui.de - a multi-page explainer with cheat sheets, some broken links
• http://download.oracle.com/docs/cd/E19957-01/806-3568/ncg_goldberg.html - a technical explanation of the implementation of floating-point numbers

JavaScript does not have the same language features as C# for extended-precision floats or decimal constants. The first site suggests the decimal.js library for arbitrary-precision decimal calculations.