Posted by Alice on .
You are having a pool party and invite 2 of your best friends. These two friends each invite two other people. Each of these 2 people invite 2 people that haven't been invited. How many people will be invited if this process continues for four rounds?

math 
Reiny,
number of people invited in round 1 = 2
number of people invited in round 2 = 4
.....
total invited = 2 + 4 + ....