A circuit training workout starts with a certain number of exercises and for each new exercise, decreases the number of repetitions by 1 (e.g. 20 squats, 19 pushups, 18 crunches, etc.) all the way down to 1 (e.g. the last exercise is 1 jumping jack). How many total repetitions are completed if there are n exercises?
One exercise
One total repetition
Two exercises
Three total repetitions
Three exercises
Six total repetitions
Four exercises
Ten total repetitions
It should be fairly clear that the number of total repetitions of all the exercises is the sum of consecutive integers. Check out the Sum of Integers solution for a "trick" on how to find this sum really quickly.
If we represent the problem visually in the correct way, we can also see connections to the solution of the Triangular Numbers problem.