Using Excel Spreadsheets are very useful computer programs which are used primarily for processing columns of numbers. It will add up columns of numbers, and if you change a number in the column, the total is automatically corrected. You can use a spreadsheet to do your checkbook, keep records for a business, prepare your taxes, or keep any kind of records. I use one to keep the grades for our classes - if I make a correction or add an item the total grade is automatically corrected. I can also sort the rows by student number instead of by name.
Spreadsheets can do all kinds of arithmetical operations.
Rutgers has plenty of copies on the student server on clam - you enter through Windows. In a Spreadsheet, columns are labeled with letters and rows with numbers. We enter our data in columns. Put the years or the category labels in the first column. Put the numbers in the second column.