🎙 Introduction / परिचय
Clock & Calendar में basic time–angle, gain–loss of time और day calculation पूछे जाते हैं।
Delhi Police level पर questions बहुत आसान होते हैं — बस 3–4 formulas याद रखें।
⏰ Clock – Important Concepts
1. Angle between hands:
Angle = |30H − 5.5M| degrees
(H = hour, M = minutes)
2. Coincidence (घंटा व मिनट सुई साथ में):
Every hour once (approx.) except between 11–1
Total 22 times in 12 hours.
3. Right angle (90° apart):
Occurs 44 times in 24 hours.
Example 1:
Find angle at 3:00.
H=3, M=0 → |30×3 − 5.5×0| = |90−0| = 90°
Example 2:
Angle at 5:30?
H=5, M=30 → |30×5 − 5.5×30| = |150 − 165| = 15°
📅 Calendar – Important Concepts
1. Ordinary year = 365 days → 1 extra day ⇒ day shifts by 1
2. Leap year = 366 days → 2 extra days ⇒ day shifts by 2
Leap year rule: divisible by 4 and not by 100; or divisible by 400.
Example 3:
If 1 Jan 2023 is Sunday, what is 1 Jan 2024?
2023 is not leap → shift by +1 day → Monday
Example 4:
Is 2024 a leap year?
2024 ÷4 = 506 → yes, leap year → 366 days.
✔ Practice MCQs – Clock
- Angle at 6:00?
Ans: 180°
- Angle at 9:00?
Ans: 90°
- Angle at 12:30?
Ans: 165°
- How many times minute & hour hands coincide in 12 hours?
Ans: 11
- How many right-angle positions of clock hands in 12 hours?
Ans: 22
✔ Practice MCQs – Calendar
- If today is Monday, after 10 days it will be?
Ans: Thursday
- If 1 Jan is Friday in a non-leap year, what is 1 Jan next year?
Ans: Saturday
- How many days in leap year?
Ans: 366
- Is 2100 a leap year?
Ans: No (divisible by 100 but not 400)
- If today is Wednesday, what was 3 days ago?
Ans: Sunday
🔥 Challenge Question
Find the angle between hour and minute hand at 7:20.
H=7, M=20
Angle = |30×7 − 5.5×20| = |210 − 110| = 100°
Answer: 100°
Motivation: Clock & Calendar के सिर्फ 4–5 formulas strong कर लो —
फिर हर सवाल 30–40 सेकंड में हो जाएगा। 🚓🔥