# Off Topic > Tips and Tutorials >  >  Disregarding blank cells when performing calculations

## Harager

I found out that in above written formula there was made a mistake, it should be :

IF(AND(ISNUMBER(A2);ISNUMBER(B2)); A2*B2; " ")

where between ISNUMBER(A2) and ISNUMBER(B2) there should be ';' and not ',' 

With friendly greetings,

Harager

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## Moshe

Is there no way to request #Value to be replaced with an empty string?

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## ExcelTip

Problem:	

Columns A:B contain numbers, as well as empty cells.
How could we multiply each number in column A with the matching number in Column B without getting false results or errors?										

Solution:	

Using the ISNUMBER function will allow us to validate the values prior to the calculation.
Thus, when failing to multiply a pair of values, the formula will return a blank cell, rather than an error or 0.
Following is the formula:
=IF(AND(ISNUMBER($A$2:$A$5), ISNUMBER($B$2:$B$5)),A2*B2,\"\"\"\")									

Example:	


List1___List2___Result						
2_______3_______6						
5	   							
8							
11______4_______44

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## gms_nm

This formula is more useful when the cell has a non numeric entry, say a text entry. In which case but for this formula it would have given a result "#VALUE!"
Which would have meant one could not sum the value up.

If the cell is blank, without the formula it would give a result "0", with the formula it returns with a blank text entry.

This forumla is more appropriate termed as "ignoring text cells when performing calculations"

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