One quick and easy way to add values in Excel is to use AutoSum. Just select an empty cell directly below a column of data. Then on the Formula tab, click AutoSum > Sum. Excel will automatically sense the range to be summed. (AutoSum can also work horizontally if you select an empty cell to the right of the cells to be summed.)
Add based on conditions
Use the SUMIF function when you want to sum values with one condition. For example, when you need to add up the total sales of a certain product.
Use the SUMIFS function when you want to sum values with more than one condition. For instance, you might want to add up the total sales of a certain product, within a certain sales region.