Attempted to divide by zero

When exporting the Telerik RadGrid to Excel, the "Attempted to divide by zero" exception is thrown. The grid contains calculated columns such as getting the percentage, etc.

  

In Mathematics, dividing a number by zero is undefined. We can check first if the divisor is zero and return zero as the result.

String.Format("{0:0.00%}", group.Sum(i => i.myDivisor) == 0 ? 0 : group.Sum(i => i.myDividend) / group.Sum(i => i.myDivisor) ),