Year 5 Mental Maths Facts Quiz Fiendish Level. How many seconds in an hour?. 3600 seconds. How many weeks in 11 years?. 572 weeks. How many days are there in the first 6 months of the year (assuming it is not a Leap Year)?. 181 days. What is 13:13 in 12 hour (analogue) time?. 1.13pm.