There are 10 soccer teams in the sunnydale soccer league. each team will play every other team once. how many games will there be in total?

1-2      2-3     3-4     4-5     5-6     6-7     7-8     8-9     9-10
1-3      2-4     3-5     4-6     5-7     6-8     7-9     8-10
1-4      2-5     3-6     4-7     5-8     6-9     7-10
1-5      2-6     3-7     4-8     5-9     6-10
1-6      2-7     3-8     4-9     5-10
1-7      2-8     3-9     4-10
1-8      2-9     3-10
1-9      2-10
1-10

each team is numbered 1 to 10
THERE ARE 45 GAMES