# Mysterious Number Precision Error

**URL:** <https://forum.kirupa.com/t/mysterious-number-precision-error/291561>\
**Category:** flash\
**Created:** [July 1, 2009, 1:40pm UTC](https://forum.kirupa.com/t/mysterious-number-precision-error/291561 "2009-07-01T13:40:17Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Vector\_Media](https://avatars.discourse-cdn.com/v4/letter/v/d07c76/32.png) [@Vector\_Media](https://forum.kirupa.com/u/Vector_Media)\
**Post date:** [July 1, 2009, 1:40pm UTC](https://forum.kirupa.com/t/mysterious-number-precision-error/291561/1 "2009-07-01T13:40:17Z")

</div>

Try this:

var num:Number = 1;

num -= 0.2  
trace( num );

num -= 0.2  
trace( num );

num -= 0.2  
trace( num );

num -= 0.2  
trace( num );

num -= 0.2  
trace( num );

num -= 0.2  
trace( num );

It will output this:

0.8  
0.6000000000000001  
0.4000000000000001  
0.20000000000000007  
5.551115123125783e-17  
-0.19999999999999996

Do you have any logical explanation about that???