There are a number of solutions for this. The simplest is to use the SUMIF function on the data tab. This takes threes values =SUMIF(range, criteria, sum range). The range would be the account number column, the criteria would be a cell with the desired account number, and the sum range would be the column of deductible amounts. Another approach would be to create a pivot table report from the data tab with sum totals of deductibel amount by account number.