#DIV/0! is not a comic book version of someone cursing. It’s the error message that you receive in an Excel worksheet whenever you attempt to divide by zero. If you remember grade school math class, zero divided by any number is zero. However, unless you were born on Gallifrey, dividing any number by zero is a mathematical impossibility. Since Excel cannot solve the formula, it returns #DIV/0! as shown in the following screen shot.

As you can see from this image, the #DIV/0! error cascades throughout the spreadsheet. Cells D8 and D10 return the same error message because one of the cells that is being summed and averaged contains the error condition. The error in cell D10 causes cell D12 to return an error. Although you cannot prevent a zero from appearing as a divisor in a formula, you can prevent the error condition from cascading by wrapping all of your division formulas inside of the IF function.

The basic structure of the IF function is: =IF(condition to test,return if true,return if false). In this example we want to test whether the numbers in column C equal zero. If they do, return the number zero. If they do not, perform the original division formula. As shown in the following screen shot, the division error messages have disappeared and the formulas in D8,D10, and D12 return an answer.

Notice that cells D5 and D6 both return zero, but for different reasons. One way to stop the error messages but yet not return the number zero is to enter some text as the true result from IF function. In the following example the IF function has been changed to display a dash (-) whenever the divisor is zero.

**WARNING – **although the SUM function in cell D8 returned the same answer in both of the two previous screen shots, the AVERAGE funtion in cell D10, and the formula in cell D12 have different answers, as highlighted in the red box. This is caused by the way Excel functions work. The SUM function treats text as a zero. Thus summing a cell containing a zero or a cell containing text results in the same answer. However, the AVERAGE function **ignores** any cells containing non-numerical data. Therefore the first IF example is averaging *five* cells, two of which contain zero, while the second IF example is averaging *four cells*, one of which contains zero. Depending on your application this could have a significant impact. [In these instances you may want to use the AVERAGEA function. This function treats text as a zero, similar to the SUM function.]

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