Calculator Does Not Reliably Subtract Two Numbers in Windows (72540)


The information in this article applies to:

  • Microsoft Windows 3.0
  • Microsoft Windows 3.0a
  • Microsoft Windows 3.1
  • Microsoft Windows 3.11
  • Microsoft Windows for Workgroups 3.1
  • Microsoft Windows for Workgroups 3.11
This article was previously published under Q72540

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.

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 from the Microsoft Web site.

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
Modification Type:MinorLast Reviewed:7/7/2005
Keywords:KB72540
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