Calendar & Clock Problems: Tricks to Solve in Seconds

Calendar and clock questions carry 1-2 marks each but can be solved in under 30 seconds with the right tricks.

Calendar: Odd Days Method

Odd days = remainder when total days divided by 7. 1 ordinary year = 1 odd day. 1 leap year = 2 odd days. 100 years = 5 odd days. 200 years = 3 odd days. 300 years = 1 odd day. 400 years = 0 odd days.

Calendar Quick Codes

Sunday=0, Monday=1, Tuesday=2... Saturday=6. To find the day: Calculate total odd days from reference date and count forward from the known day.

Clock: Angle Calculation

Angle between hands = |30H - 5.5M| where H=hours, M=minutes. Hands overlap at: 12:00, ~1:05, ~2:10, ~3:16, ~4:22, ~5:27, ~6:33, ~7:38, ~8:44, ~9:49, ~10:55. That's 11 times in 12 hours (not 12!).