IMAS 2021 — Middle Primary Grades 3–4 — Round 1 Question 20

The three circles below have some number of points on their circumference. Connect all the points on the same circle using straight lines and count the number of regions these segments have partitioned the circle into.



2 points,

2 regions.



3 points,

4 regions.



4 points,

8 regions.

If there are 5 points on the circumference of a circle, how many regions have been partitioned at the most?