John :)

This page lists questions and answers that were posted by visitors named John :).

Questions

The following questions were asked by visitors named John :).

Linda's teacher divided the class into groups of five and required each member of a group to meet with every other member of that group. How many meetings will each group have?

Answers

The following answers were posted by visitors named John :).

I know the answer is 10, but the problem is I can't find out the formula :/ if I only show the answer I won't get any credit and it'll be marked wrong.