Updated Calculator Accessory for Windows

This article was previously published under Q124345

Introduction

The WW1138.EXE file contains an updated version of the Calculator accessory that is shipped with Microsoft Windows 3.1x and Windows for Workgroups 3.1x. Previous versions of Calculator display simple subtraction errors when you subtract two numbers that include values to the right of the decimal point. While Calculator is determining how to display the solution, it encounters a loss of precision and shows an incorrect answer.

NOTE: This rounding error is unrelated to the floating-point unit (FPU) in the Intel(R) Pentium(R) chip. This problem occurs only in Calculator and does not affect Windows, other components in Windows, or other Windows-based applications.

In addition to correcting the problem described above, the new rounding algorithm in Calculator causes it to perform more like most hand-held calculators. For example, if you enter the following equation in the updated Calculator accessory or in a hand-held calculator the result is 0.9999. The result in previous versions of Calculator is 1.0. The value 0.9999 is generated because significant digits are lost by adding and subtracting 10. This is a secondary effect of the changes made in Calculator to correct the precision errors.

To install the updated files

The following file is available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.

1. Download the WW1138.EXE file from the Microsoft Download Center to an empty folder.
2. Double-click the WW1138.EXE file you downloaded in step 1.
3. Quit Windows, or open an MS-DOS command prompt within Windows.
4. Rename the existing CALC.EXE file in your Windows directory. For example, if Windows is installed in a directory on drive C called WINDOWS, type the following commands, pressing ENTER after each line:
   cd\windows
   ren calc.exe calc.old
5. At an MS-DOS command prompt, type the following and press ENTER
   copy <source>:\calc.exe <location>
   where <source> is the directory containing the file you downloaded from online services, and <location> is the path to your Windows directory.
   
   For example, if you downloaded the WW1138.EXE file from online services to C:\DOWNLOAD and C:WINDOWS is the path to your Windows directory, type:
   copy c:\download\calc.exe c:\windows

Steps to Reproduce Problem Using Previous Versions of Calculator

1. To perform this test, choose two numbers that include values to the right of the decimal point (for example, 12.52 and 12.51).
2. Double-click the Calculator icon in the Accessories group.
3. Enter the larger number first (for example, 12.52).
4. Press the MINUS SIGN (-).
5. Enter the smaller number (for example, 12.51).
6. Press the EQUAL SIGN (=).

Note that in this example you do not receive .01, the expected result. Instead, you receive one of the following: The updated Calculator accessory displays the correct result, which is .01.