MOD Function and Mod Operator Return Different Values

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SYMPTOMS

In Microsoft Excel, the result returned by the worksheet MOD function may be different from the result returned by the Microsoft Visual Basic for Applications Mod operator.

CAUSE

This problem occurs if you use the MOD function with either a negative number or a negative divisor, but not both negative. In general, the MOD function returns the remainder after a number is divided by a divisor. The built-in Microsoft Excel function uses the formula
MOD(n,d)=n-d*INT(n/d)
where n is the number and d is the divisor. If the divisor is a positive number, the MOD worksheet function and the Visual Basic for Applications Mod operator return the same results. For example, =MOD(17,3) on a worksheet and 17 Mod 3 on a module sheet will return the same value of 2.

The difference between the MOD worksheet function and the Mod operator occurs because of the way Microsoft Excel uses the INT function. The INT function returns the first negative integer less than or equal to the number. For example, =INT(17,-3) will return -6, because 17 divided by -3 is equal to -5.6666667 and the closest integer that is less than or equal to -5.6666667 is -6.

The result of using the INT function is what makes the worksheet MOD function return a different value than the Mod operator. The Mod operator does not use the same formula containing the INT function and, therefore, it returns a different result with a negative number or a negative divisor.

WORKAROUND

To return the same answer that the Mod operator returns with a negative number or a negative divisor, enter the following formula into a worksheet instead of using the built-in Microsoft Excel MOD function
=N-D*QUOTIENT(N,D)
where N is the number and D is the divisor.

NOTE: This formula only gives the same answer as the Mod operator when both the number and the divisor are integers.

NOTE: You must have the Analysis ToolPak installed to use the QUOTIENT function.

For additional information on both the INT and MOD functions, please see the following articles in the Microsoft Knowledge Base:
119083 XL: MOD() Function Returns #NUM! Error Value

124107 XL: Can't Specify Number of Digits with Fix() or Int()

REFERENCES

Excel 97

For more information about the MOD worksheet function, click Contents And Index on the Help menu, click the Index tab in Help, type the following text
MOD
and then double-click the selected text to go to the "MOD worksheet function" topic. If you are unable to find the information you need, ask the Office Assistant.

For more information about the Mod Visual Basic for Applications operator, from the Visual Basic Editor, click the Office Assistant, type Mod. click Search, and then click to view "Mod operator."

NOTE: If the Assistant is hidden, click the Office Assistant button on the Standard toolbar. If the Assistant is not able to answer your query, please see the following article in the Microsoft Knowledge Base:
176476 OFF: Office Assistant Not Answering Visual Basic Questions

Excel 7.0

For more information about the MOD function or the Mod operator, click the Answer Wizard tab in Microsoft Excel 7.0 Help, type the following text
MOD
and then double-click the selected text to go to the desired topic.

Properties

Article ID: 141178 - Last Review: August 17, 2005 - Revision: 1.3
APPLIES TO
• Microsoft Excel 97 Standard Edition
• Microsoft Excel 95 Standard Edition
• Microsoft Excel 5.0 Standard Edition
Keywords:
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