Arithmetic Progression
From Gauss's story to the justification of the formula
The school narrative associated with Gauss highlights the grouping of the ends of a sum. The idea is valid beyond that story: we can demonstrate it for any finite arithmetic progression.
Your turn to investigate: Write 2, 5, 8, 11, 14 and, below, the same sequence in reverse. Add the columns. Why is the result for each column the same?
Discover the historical source on MacTutor, from the University of St Andrews.
