If there are 45 games played in a season where each team plays the other one once, how many teams were there?

Question

This was part of a sequence and series review.

Answer 1

Let t be the number of teams

then the number of games is

45 = t ( t - 1) / 2

because each team does not play itself and

We don’t want to count a pair twice ( A playing B and B playing A should count as 1, and not 2)

Solve for t.