MATHS
posted by chelsea .
how much money would you have after 20 weeks if you were given 5c the first week, 10c the second, 20c the third, 40c the fourth, and so on?

looks like a geometric series
5 + 10 + 20 + 40 + ... for 20 terms
a = 5 , r = 2
Sum(2) = 5(2^20  1)/(21) = 5242875 c