There is juice sold at a store which you can exchange for another new bottle with three empty bottles.
When you buy 20 bottles of juice, how many bottles of juice can you drink in all?
Answer
29 bottles
Solution
When you buy 20 bottles of juice, you can get six new bottles since 20 / 3 = 6 remainder 2.
When you drink 6 bottles, you have 8 empty bottles (6 + remainder 2 = 8).
Then you can get two new bottles since 8 / 3 = 2 remainder 2.
When you drink 2 bottles, you have 4 empty bottles (2 + remainder 2 = 4).
Then you can get one new bottle since 4/3 = 1 remainder 1.
The number of bottles you can drink is 20 + 6 + 2 + 1 = 29 bottles.
