The more professional statement is this: 13+ 1 (step). If the last wooden step is flush with the second floor, it is called: 13+0 (step), which is easy to distinguish.
Fibonacci sequence
The definition of Fibonacci sequence is Italian mathematician Leonardo Fibonacci, who was born in 1 170 and died in 1250. His birthplace is Pisa.
He is called "Leonardo of Pisa". 1202, he wrote the book Liber Abacci. He was the first European to study the mathematical theories of India and Arabia.
His father was hired as a diplomatic consul by a business group in Pisa and stationed in Algeria, so Leonardo was able to study mathematics under the guidance of an Arab teacher. He also studied mathematics in Egypt, Syria, Greece, Sicily and Provence. In addition, Fibonacci sequence is also widely used in computer C language programming problems.