In Excel when you refer the cell where the formula lies in, it is a circular reference as you get the workbook confused... For Ex: You are writing a formula in A1 and the formula you enter is =Sum(A1:A5) this is a circular reference as you have the formula in A1 and you want the sum to include A1 Now the frustrating part in the circular reference error message is that it doesn't point you to the location which has the error. Thankfully there is an easy way to figure out which cells have circular reference: To locate circular references: Go to Formulas --> Error Checking --> Circular Reference (Excel 2010) Once you hover over it, you will see all the cells which have circular references...you can then rectify the errors... there are resources which explain in good detail: Video or in excel help go to "Excel 2010 Home > Excel 2010 Help and How-to > Formulas > Correcting formulas"
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