Problem
COM-B1-M10-P001 Five Stairs
#1
★☆☆☆☆ Level 1 of 5
In how many ways can one climb \(5\) stairs if each move is \(1\) or \(2\) stairs?
Use \(a_n=a_{n-1}+a_{n-2}\).
Let \(a_n\) be the number of ways. Then \(a_0=1\), \(a_1=1\), and \(a_n=a_{n-1}+a_{n-2}\). Thus \(a_2=2\), \(a_3=3\), \(a_4=5\), \(a_5=8\).
First basic count by last step.