In mathematics, the Fibonacci numbers form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. The beginning of the sequence looks like this:
0+1=1 1+1=2 1+2=3 2+3=5 3+5=8 5+8=13 8+13=21 13+21=34 21+34=55 45+55=89 . . . What is the next number in the sequence?

Fibonacci numbers are named after Italian mathematician Leonardo of Pisa, later known as Fibonacci.
They also appear in biological settings, such as branching in trees, the arrangement of leaves on a stem, the fruit sprouts of a pineapple, the flowering of an artichoke, an uncurling fern, and the arrangement of a pine cone’s bracts. You can see some examples here.