Alternatively, since the cells are consecutive, you could also use the SUM feature to sum multiple columns in Excel, based on criteria. In this instance, you would place the cursor in the C10 cell ...

How to Add Cells Across Multiple Spreadsheets. Adding data that spans multiple Excel spreadsheets might appear daunting at first, but Microsoft simplifies the task with two referencing methods.

Sometimes it's necessary to split cells in a spreadsheet, and Microsoft Excel makes it easy enough to do.