Microsoft KB Archive/137527

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XL: Value of 15-Digit Numbers May Be Changed Unexpectedly

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The information in this article applies to:


 * Microsoft Excel for Windows, versions 3.0, 3.0a, 4.0, 5.0, 5.0c
 * Microsoft Excel for OS/2, version 3.0
 * Microsoft Excel for the Macintosh, versions 3.0, 4.0, 5.0, 5.0a
 * Microsoft Excel for the Power Macintosh, versions 5.0, 5.0a
 * Microsoft Excel for Windows NT, version 5.0
 * Microsoft Excel for Windows, versions 7.0, 7.0a

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SUMMARY
This article contains information relating to the "15-digit number" error in Microsoft Excel that was discovered in September 1995. The "More Information" section of this article contains a full description of the problem, as well as information about how to resolve it.

In the versions of Microsoft Excel listed above, the value of certain 15- digit numbers may be unexpectedly changed when they are entered in a worksheet cell or when they are calculated by a formula in a worksheet cell. The three numbers are as follows:

140737488355328

281474976710656

562949953421312 If you enter a variation of these numbers (for example, 1.40737488355328), or if you calculate a variation of one of these numbers, the number may be resolved to a different value, such as 0.64 (or some multiple of 0.64).

Beginning on October 6, 1995, a patch became available for Microsoft Excel that corrects this problem. See question 11 in the "More Information" section for information about how to obtain the patch.

This problem is also corrected in Microsoft Excel 7.0a, Microsoft Excel 97, and Microsoft Excel 98 Macintosh Edition.

MORE INFORMATION
The following section addresses common questions regarding the "15-digit number" problem.

 Q. I heard that there is a problem where Microsoft Excel incorrectly changes the values of some specific numbers. What's the situation?

A. In Microsoft Excel 5.0 and 7.0, there is an error that causes three specific sequences of 15 digits to change their values either when you type them as individual entries, or when you derive them from specific functions. Microsoft has created a solution in the form of a patch that is available online and on floppy disk. Q. Can you tell me what that means in more common terminology?

A. What this means is that if you type one of three specific 15-digit numbers, or derive the number as the result of a formula, Microsoft Excel might change the value of the number. Q. What are the chances that I have been affected?

A. Although it is hard to have an exact number, we believe this problem only affects a very small number of customers. In fact, based on our internal analysis, the likelihood of any one of these sequences of digits appearing in a customer's spreadsheet is approximately 1 in 5 billion. Remember, the only way that this problem will affect you is if you have one of the three specific combinations of 15 digits. Q. If there is such a small likelihood of this problem occurring, why worry about fixing it?

A. Our customers depend on Microsoft Excel to compute their numbers accurately and we want them to feel confident when using the product. Even though the probability of one of our customers having a problem is low, we can't judge the probability for each and every customer. Our approach is to distribute all of the facts regarding this problem so that you can determine for yourself if you need the patch. The solution is available to all customers who own Microsoft Excel or Microsoft Office. This patch is available at no charge beginning October 1, 1995 in the U.S. Q. What are you doing to fix this problem?

A. We have created a solution that will correct this error. It is available in the form of a patch beginning on October 1, 1995 in the U.S. Q. So, what are the numbers that cause this error?

A. The specific sequences of digits are: 140737488355328, 281474976710656 and 562949953421312. The decimal point may be in different places. In addition, if you are dealing with calculations, the result has to be one of these three sequences of digits, plus or minus a number less than approximately one-half of the next decimal, times a power of 10. This is only a problem when you refer to the result in the following functions: the INT, CEILING, FLOOR, ROUNDUP, and IF functions. In addition, the ROUNDDOWN and MOD functions may be affected. Q. Why are these specific numbers affected?

A. The common bond between these numbers is that they happen to be 2 raised to the 47th, 48th, and 49th power, respectively. Q. Does this mean I have to check to make sure that any 15-digit numbers in my files have been changed by Microsoft Excel?

A. No. Unless you entered in one of the three specific sequence of digits mentioned above, or have used one of the specific formulas mentioned above with very long numbers, your numbers should be correct. To double-check your numbers, do the following: install the patch, open a file, and press CTRL+ALT+F9. When you press this key combination, the patch corrects any numbers that were incorrectly derived from the functions mentioned in this article.</li> Q. How did you find out about this problem?

A. One of our customers found the error while working with a formula that derived the number 1.40737488355328. This customer's work required that he create a formula in Microsoft Excel that explicitly calculated 2 raised to the 47th power, and derive the integer portion of it. We were not previously aware of this error and are grateful that it was brought to our attention.</li> Q. What versions of Microsoft Excel does this problem affect?

A. We have found this problem in versions of the product dating back to Excel 3.0 for Windows, the Macintosh, and OS/2. Other affected versions include Microsoft Excel 4.0 for Windows and the Macintosh, Microsoft Excel 5.0 for Windows, Windows NT, and the Macintosh, and Microsoft Excel for Windows 95. The patch is available at no charge for any of our customers using any of these versions of Microsoft Excel.</li>  Q. How do I get the patch?

A. You can call the Microsoft Order Desk at (800) 360-7561 and the patch will be sent to you at no charge.

For additional information, including information about how to obtain the patch, please see the following articles in the Microsoft Knowledge Base: "Q128650 XL7 Patch Available: 15-Digit Number, Linking, and Transpose" "Q128332 WE1254: 15-Digit Number Patch for MS Excel Version 5.0c"</li></ol>

For additional information, please see the following article in the Microsoft Knowledge Base:

"Q139803 XL: Wrong Value When Values Pasted with Paste Special Command" Additional query words: 3.00a 5.00a 5.00c 7.00a katt 2^47 2^48 2^49 fifteen fifteen-digit

Keywords : xlformula

Version : MACINTOSH:3.0,4.0,5.0,5.0a; WINDOWS:3.0,3.0a,4.0,5.0,5.0c; :3.0; Win95:7.0,7.0a; winnt:5.0

Platform : MACINTOSH Win95 WINDOWS winnt

Issue type : kbbug

Technology :