Question

Sarah left a bunch of keys on top of the stairs. She saw a missing number on the topmost stair and wanted to solve the puzzle before getting the keys. Can you help her out?

Answer 1

Let's look at the stairs one by one.
The number 9 lies between 8 and 10 and is placed above them.
The number 11 lies between 10 and 12 and is placed above them.
Hence, the number between the two numbers lies above them.
Using this pattern, the number 13, which lies between 12 and 14, is placed above them in the 3rd row.
The number 10 lies between 9 and 11 and is placed above them.
The number 12 lies between 11 and 13 and is placed above them.

Let's find the number on the topmost stair. According to this pattern, the number in the topmost stair is 11.