Medium
How many 8's are there in the following sequence which are preceded by '5' but not immediately followed by '3'?
5 8 3 7 5 8 6 3 8 5 4 5 8 4 7 6 5 5 8 3 5 8 7 5 8 2 8 5
Explanation
Explanation
The qualifying 8s occur in 5-8-6, 5-8-4, 5-8-7 and 5-8-2. Therefore the count is 4.
PRO TIP
Re-check your working by substituting the answer back into the original question.