Railways Notes / General Intelligence & Reasoning / Chapter 17
Chapter 17 of 22

Clock & Calendar

The angle-between-hands formula and the odd days concept — two compact, formula-driven topics grouped together.

📖 ~4 min read 🧠 RRB NTPC / Group D — Reasoning

Clock: Angle Between Hands

Angle = |(30×H) − (11/2)×M| degrees, where H = hour, M = minutes
💡 Example: Angle at 4:20 → |(30×4) − (11/2)×20| = |120−110| = 10°

Calendar: Odd Days Concept

  • 1 ordinary year (365 days) = 52 weeks + 1 odd day
  • 1 leap year (366 days) = 52 weeks + 2 odd days
Odd DaysDay
0Sunday
1Monday
2Tuesday
3Wednesday
4Thursday
5Friday
6Saturday
Leap year rule: divisible by 4, EXCEPT century years, which must be divisible by 400 (2000 is a leap year, 1900 is not)

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