A shop sells 1 chocolate for $1. You can exchange 3 wrappers for 1 chocolate. If you have $75, how many chocolates can you get?
Answer
112 chocolates.
You buy 75 chocolates with $75. After eating the 75 chocolates, you will have 75 wrappers. Then exchange the 75 wrappers for 25 chocolates.
After eating the 25 chocolates, you will have 25 wrappers. Exchange 24 wrappers for 8 chocolates. You have 8 chocolates with 1 wrapper.
After eating the 8 chocolates, you will have 8 wrappers. Since you already had 1 wrapper, now you will have a total of 9 wrappers. Exchange the 9 wrappers for 3 chocolates.
Lastly exchange the 3 wrappers for 1 more chocolate.
So with $75, you got 112 (75 + 25 + 8 + 3 + 1) chocolates.