Fibonnaci's Rabbits

It all starts with a pair of bunnies. They grow up and mate. Then they have babies.

1 We start with one pair of babies.

1 One pair of babies grow up in a month and mate.

2 The pair has a pair of babies in a month. The pair mates. We have two pair.

3 Now the babies grow up and mate. The first pair has another pair of babies. We have three pair of rabbits.

5 We have the three pair of rabbits from the month before. Two pair of rabbits were old enough to have a pair of rabbits. This totals five pair of rabbits.

8 Now we have the five pair of rabbits from the previous month. There were three pair of rabbits old enough to have a pair of bunnies. So, the five from before and the three new pair makes eight pairs of rabbits.