Question

In the following number sequence how many 4's are there that are immediately preceded by 6 and immediately followed by 5?
3 4 2 6 5 4 3 6 4 5 9 8 6 4 5 3 8 7 4 6 8 2 1 7 6 4 5 8 6 4 5 9 7 4 5

Answer 1

3 4 2 6 5 4 3 $\underset{1}{\underset{–}{645}}$ 9 8 $\underset{2}{\underset{–}{645}}$ 3 8 7 4 6 8 2 1 7 $\underset{3}{\underset{–}{645}}8\underset{4}{\underset{–}{645}}$ 9 7 4 5
There are four such 4's which are immediately preceded by 6 and immediately followed by 5.