Calculator Does Not Reliably Subtract Two Numbers in Windows

 Last reviewed: January 13, 1995
Article ID: Q72540
The information in this article applies to:
  • Microsoft Windows operating system versions 3.0, 3.0a, 3.1, 3.11
  • Microsoft Windows for Workgroups versions 3.1, 3.11

SYMPTOMS

Microsoft Windows Calculator (CALC.EXE) does not reliably subtract two numbers with decimal values. This problem occurs in both modes (standard and scientific) of Calculator.

CAUSE

Calculator does not round the decimal values properly. While Calculator is determining how to display the solution, it encounters a loss of precision and shows an incorrect answer.

RESOLUTION

Windows 3.0

Microsoft has confirmed this to be a problem in Windows 3.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

Windows 3.1x, Windows for Workgroups 3.1x

To correct this problem in Windows 3.1x and Windows for Workgroups 3.1x, obtain the updated CALC.EXE file that is included with the PSS Application Note "WW1138: Updated Calculator Accessory for Windows."

For more information about this Application Note, please see the following article in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q124345
   TITLE     : WW1138: Updated Calculator Accessory for Windows

MORE INFORMATION

Steps to Reproduce Problem

  1. Start Calculator.

  2. Input the largest number to subtract first (for example, 12.52).

  3. Press the MINUS SIGN (-) key on the numeric keypad.

  4. Input the smaller number that is one unit lower in the decimal portion (for example, 12.51).

  5. Press the EQUAL SIGN (=) key on the numeric keypad.

Subtracting 12.51 from 12.52 results in one of the following incorrect numbers: 

   0.00
   0.0099999999
   0.010000001

KBCategory: kbtool kbbuglist kbappnote
KBSubcategory: win30 win31 wfw wfwg
Additional reference words: 3.0 3.00 3.1 3.10 subtraction 3.11 appnote
ww1138.exe

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Last reviewed: January 13, 1995
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