Windows 10 Calculator

Microsoft today released a new Windows 10 Build 17639 for Skip Ahead Insiders with many improvements and fixes. The company released the new Insider build to the Windows 10 users enrolled in Skip Ahead Ring.

The company pushed lots of fixes and improvements in the latest Windows 10 Build 17639 for Skip Ahead Insiders. However there is one more important bug pertaining to the Windows Calculator which was also fixed in the latest build but was not reported in the change log.

The Windows Calculator bug has been a long standing bug which was found in the calculator app of Microsoft’s Windows 7 operating system. The bug in the calculator app doesn’t give you the correct answer when you try to calculate square root of 4 and then subtract 2.

The answer should be 0, but due to an arbitrary precision arithmetic library bug the calculator provided a wrong answer. This issue existed since close to a decade now which finally received a fix with the latest Redstone 5 build 17639.

The Calculator bug was seen on 3 out of 4 devices and hence the number of users effected could be on a higher side. The Windows Calculator bug existed on company’s Windows 7  and has been continued to the Windows 8.1 and then to Microsoft’s new operating system Windows 10 since there was no change in the library which was used in the Calculator app in Windows 7.

As per Raymond Chen’s explanation on Microsoft’s Developer page he says: “Even if the value you are taking the square root of happens to be a perfect square, the calculator doesn’t realize that. It doesn’t try to calculate an integer square root first, and then fall back to the floating point version if the integer square root fails to produce an exact result. It just goes for the square root via the extended precision library.”

If you have encountered the Calculator bug earlier and are currently enrolled in Skip Ahead Ring, the latest Insider Windows 10 Build 17639 is available for download with the fix. Do let us know in the comments below if the Calculator bug has been fixed for you.

  • cmolinap

    In my desktop PC (Windows 10 Pro Version 1709 Build 16299.334, 64 bits) Calculator give me the right anwser: Zero (0); but, in my Lumia 950 (Windows 10 Mobile Version 1709 Build 15254.313) doesn’t: -8.164846955514…..e-39

  • Beavis

    The calculator bug goes back another two Windows versions to Windows XP (maybe more, but I had no older PC to test with). And MS knew about it. On their website, there were quite a few responses from MS staff who used a lot of advanced tech concepts & jargon in defense of this bug. As such, I’m very surprised to learn they’re finally going to fix it. Why this change in attitude from MS? (I tested the Linux calculator which didn’t have this bug, nor have I heard about any)