Reasoning Notes - Calendar with Examples
1. Basic Calendar Facts
- A year has 365 or 366 days : āĻāĻāĻž āĻŦāĻā§°āĻ¤ ā§Šā§Ŧā§Ģ āĻŦāĻž ā§Šā§Ŧā§Ŧ āĻĻāĻŋāĻ¨ āĻĨāĻžāĻā§
- A month has 28 / 29 / 30 / 31 days : āĻāĻāĻž āĻŽāĻžāĻšāĻ¤ ā§¨ā§Ž / ā§¨ā§¯ / ā§Šā§Ļ / ā§Šā§§ āĻĻāĻŋāĻ¨ āĻĨāĻžāĻā§
- A week has 7 days : āĻāĻāĻž āĻ¸āĻĒā§āĻ¤āĻžāĻšāĻ¤ ā§ āĻĻāĻŋāĻ¨ āĻĨāĻžāĻā§
2. Ordinary Year
- Total days = 365 : āĻŽā§āĻ āĻĻāĻŋāĻ¨ = ā§Šā§Ŧā§Ģ
- February has 28 days : āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§ āĻŽāĻžāĻšāĻ¤ ā§¨ā§Ž āĻĻāĻŋāĻ¨
- Most years are ordinary years : āĻŦā§āĻāĻŋāĻāĻžāĻ āĻŦāĻā§° āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻŦāĻā§°
3. Leap Year
- Total days = 366 : āĻŽā§āĻ āĻĻāĻŋāĻ¨ = ā§Šā§Ŧā§Ŧ
- February has 29 days : āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§ āĻŽāĻžāĻšāĻ¤ ā§¨ā§¯ āĻĻāĻŋāĻ¨
- One extra day is added in February : āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§ āĻŽāĻžāĻšāĻ¤ āĻāĻāĻž āĻ āĻ¤āĻŋā§°āĻŋāĻā§āĻ¤ āĻĻāĻŋāĻ¨ āĻ¯ā§āĻ āĻšāĻ¯āĻŧ
4. Rule to Identify Leap Year
- If a year is divisible by 4, it is a Leap Year : āĻā§āĻ¨ā§ āĻŦāĻā§° ā§Ēā§°ā§ āĻŦāĻŋāĻāĻžāĻā§āĻ¯ āĻš’āĻ˛ā§ āĻ¸ā§āĻāĻā§ Leap Year
5. Century Year Rule:
- A century year (ending with 00) is not always a leap year : ā§Ļā§ĻāĻ¤ āĻļā§āĻˇ āĻšā§ā§ąāĻž āĻŦāĻā§° āĻ¸āĻĻāĻžāĻ¯āĻŧ Leap Year āĻ¨āĻšāĻ¯āĻŧ
- It is a leap year only if divisible by 400 : āĻā§ā§ąāĻ˛ ā§Ēā§Ļā§Ļā§°ā§ āĻŦāĻŋāĻāĻžāĻā§āĻ¯ āĻš’āĻ˛ā§ Leap Year āĻšāĻ¯āĻŧ
6. Important Examples
- 1920 → Leap Year (divisible by 4) : ā§§ā§¯ā§¨ā§Ļ → Leap Year (ā§Ēā§°ā§ āĻŦāĻŋāĻāĻžāĻā§āĻ¯)
- 1932 → Leap Year (divisible by 4) : ā§§ā§¯ā§Šā§¨ → Leap Year (ā§Ēā§°ā§ āĻŦāĻŋāĻāĻžāĻā§āĻ¯)
- 1989 → Ordinary Year (not divisible by 4) : ā§§ā§¯ā§Žā§¯ → āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻŦāĻā§°
- 1900 → Ordinary Year (not divisible by 400) : ā§§ā§¯ā§Ļā§Ļ → Leap Year āĻ¨āĻšāĻ¯āĻŧ
- 2000 → Leap Year (divisible by 400) : ā§¨ā§Ļā§Ļā§Ļ → Leap Year (ā§Ēā§Ļā§Ļā§°ā§ āĻŦāĻŋāĻāĻžāĻā§āĻ¯)
7. Exam Trick
- “Divide by 4 → Leap Year” : “ā§Ēā§°ā§ āĻāĻžāĻ āĻš’āĻ˛ā§ → Leap Year”
- “Century year → divide by 400” : “āĻļāĻ¤āĻŋāĻāĻžā§° āĻŦāĻā§° → ā§Ēā§Ļā§Ļā§°ā§ āĻāĻžāĻ”
===================================================================================
Day - Date Short Tricks (Calendar)
1. Odd Days – Basic Concept
- Days more than complete weeks are called Odd Days. : āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻ¸āĻĒā§āĻ¤āĻžāĻšā§° āĻĒāĻŋāĻāĻ¤ āĻŦāĻžāĻāĻŋ āĻĨāĻāĻž āĻĻāĻŋāĻ¨āĻ Odd Days āĻā§ā§ąāĻž āĻšāĻ¯āĻŧ
- 1 week = 7 days : ā§§ āĻ¸āĻĒā§āĻ¤āĻžāĻš = ā§ āĻĻāĻŋāĻ¨
- Odd days decide the day of the week : Odd Days ā§°ā§ āĻĻāĻŋāĻ¨ āĻ¨āĻŋā§°ā§āĻ§āĻžā§°āĻŖ āĻā§°āĻž āĻšāĻ¯āĻŧ
2. Odd Days in Normal & Leap Year
- Ordinary year (365 days) → 1 Odd Day : āĻ¸āĻžāĻ§āĻžā§°āĻŖ āĻŦāĻā§° (ā§Šā§Ŧā§Ģ āĻĻāĻŋāĻ¨) → ā§§āĻāĻž Odd Day
- Leap year (366 days) → 2 Odd Days : Leap Year (ā§Šā§Ŧā§Ŧ āĻĻāĻŋāĻ¨) → ā§¨āĻāĻž Odd Day
3. Odd Days in 100 / 200 / 300 / 400 Years
- 100 years → 24 leap years → 5 Odd Days : ā§§ā§Ļā§Ļ āĻŦāĻā§° → ā§ĢāĻāĻž Odd Day
- 200 years → 48 leap years → 3 Odd Days : ā§¨ā§Ļā§Ļ āĻŦāĻā§° → ā§ŠāĻāĻž Odd Day
- 300 years → 72 leap years → 1 Odd Day : ā§Šā§Ļā§Ļ āĻŦāĻā§° → ā§§āĻāĻž Odd Day
- 400 years → 97 leap years → 0 Odd Day : ā§Ēā§Ļā§Ļ āĻŦāĻā§° → ā§Ļ Odd Day
4. Month-wise Odd Days (Non-Leap Year)
- January → 3, February → 0, March → 3, April → 2, May → 3, June → 2, July → 3, August → 3, September → 2, October → 3, November → 2, December → 3
Leap Year Rule: February → 1 Odd Day : Leap Year āĻ¤ āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§āĻ¤ ā§§āĻāĻž Odd Day āĻ¯ā§āĻ āĻšāĻ¯āĻŧ
5. Weekday Number Code
- Sunday = 0 : āĻĻā§āĻāĻŦāĻžā§° = 0, Monday = 1 : āĻ¸ā§āĻŽāĻŦāĻžā§° = ā§§, Tuesday = 2 : āĻŽāĻāĻ˛āĻŦāĻžā§° = ā§¨, Wednesday = 3 : āĻŦā§āĻ§āĻŦāĻžā§° = ā§Š,
- Thursday = 4 : āĻŦā§āĻšāĻ¸ā§āĻĒāĻ¤āĻŋāĻŦāĻžā§° = ā§Ē, Friday = 5 : āĻļā§āĻā§ā§°āĻŦāĻžā§° = ā§Ģ, Saturday = 6 : āĻļāĻ¨āĻŋāĻŦāĻžā§° = ā§Ŧ
Calendar MCQs
Q1. How many odd days are there in a leap year ?
a) 0 | b) 1 | c) 2 | d) 3
Explanation: Leap year has 366 days → 366 ÷ 7 = remainder 2. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž : Leap Year āĻ¤ ā§Šā§Ŧā§Ŧ āĻĻāĻŋāĻ¨ → ā§¨āĻāĻž Odd Day
Q2. How many odd days are there in 100 years ?
a) 3 | b) 5 | c) 6 | d) 7
Explanation: 100 years → 24 leap years → 5 odd days āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: ā§§ā§Ļā§Ļ āĻŦāĻā§°āĻ¤ → ā§ĢāĻāĻž Odd Day
Q3. Which year has zero odd days ?
a) 100 years b) 200 years c) 300 years d) 400 years
Explanation: 400 years form a complete cycle. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: ā§Ēā§Ļā§Ļ āĻŦāĻā§°āĻ¤ Odd Day āĻ¨āĻžāĻ
Q4. How many odd days are there in February of a leap year ?
a) 0 | b) 1 | c) 2 | d) 3
Explanation: Leap year February has 29 days āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: Leap Year āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§ → ā§§āĻāĻž Odd Day
Q5. If a date falls on Sunday, after 7 days it will be ?
a) Monday b) Tuesday c) Sunday d) Saturday
Explanation: 7 days = complete week. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: ā§ āĻĻāĻŋāĻ¨ = āĻ¸āĻŽā§āĻĒā§ā§°ā§āĻŖ āĻ¸āĻĒā§āĻ¤āĻžāĻš
Q6. How many odd days are there in January ?
a) 1 | b) 2 | c) 3 | d) 0
Explanation: January has 31 days → remainder 3. āĻŦā§āĻ¯āĻžāĻā§āĻ¯āĻž: āĻāĻžāĻ¨ā§ā§ąāĻžā§°ā§ → ā§ŠāĻāĻž Odd Day
Exam Tips
- Remember: 400 years = 0 odd day : ā§Ēā§Ļā§Ļ āĻŦāĻā§° = 0 Odd Day
- Leap year February adds +1 : Leap Year āĻĢā§āĻŦā§ā§°ā§ā§ąāĻžā§°ā§ +ā§§
- Always convert days into odd days : āĻ¸āĻĻāĻžāĻ¯āĻŧ Odd Day āĻāĻŖāĻ¨āĻž āĻā§°āĻ
==============================================================================================