Article ID: 72540 - Last Review: September 24, 2011 - Revision: 3.0

Calculator Does Not Reliably Subtract Two Numbers in Windows

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This article was previously published under Q72540

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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.
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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.
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RESOLUTION

Windows 3.0

Microsoft has confirmed this to be a problem in Windows 3.0.
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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.
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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
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APPLIES TO
  • Microsoft Windows 3.0 Standard Edition
  • Microsoft Windows for Workgroups 3.1
  • Microsoft Windows for Workgroups 3.11
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Keywords: 
KB72540
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