Using a formula to roll up values to summary tasks

- [Instructor] Now that we have our duration indicator,…we may want to roll those values up…to the top level of the project.…To do that, we can right-click…on the duration indicator column,…select custom fields again.…This time, we can choose to roll up,…and use either a max, a minimum, or a sum.…Since we're not interested in any of those features,…since we want it to calculate what's down below,…we'll use the formula for the roll up grouping,…and we'll press OK.…Now, we have that summary line, and the total project…calculated with our duration indicator,…as it goes forward in time.…