Reasoning Notes â Day & Date : Day Codes (āĻĻāĻŋāĻ¨ā§° āĻâāĻĄ)
Century Codes : āĻļāĻ¤āĻŋāĻāĻž āĻ’āĻĄ (āĻŽā§āĻāĻ¸ā§āĻĨ āĻā§°āĻŋāĻŦāĻ˛āĻā§āĻ¯āĻŧāĻž āĻ¤āĻžāĻ˛āĻŋāĻāĻž)
- 16 → 6 : Years - āĻŦāĻā§° : 1600 – 1699
- 17 → 4 : Years - āĻŦāĻā§° : 1700 – 1799
- 18 → 2: Years - āĻŦāĻā§° : 1800 – 1899
- 19 → 0 : Years : āĻŦāĻā§° : 1900–1999
- 20 → 6 : Years : āĻŦāĻā§° : 2000–2099
- 21 → 4 : Years : āĻŦāĻā§° : 2100–2199
Easy Memory Trick : āĻ¸āĻšāĻ āĻŽā§āĻāĻ¸ā§āĻĨ āĻā§°āĻžā§° āĻā§ā§°āĻŋāĻ : 6 – 4 – 2 – 0 – 6 – 4
The code decreases by 2 each century. After 0, it starts again from 6. : āĻĒā§ā§°āĻ¤āĻŋāĻā§ āĻļāĻ¤āĻŋāĻāĻžāĻ¤ āĻ’āĻĄ ā§¨ āĻā§°āĻŋ āĻāĻŽā§āĨ¤ 0 āĻĒāĻžāĻ˛ā§ āĻĒā§āĻ¨ā§° 6 āĻā§°āĻŽā§āĻ āĻšāĻ¯āĻŧāĨ¤
Quick Exam Examples : āĻĒā§°ā§āĻā§āĻˇāĻžā§° āĻ¸āĻšāĻ āĻāĻĻāĻžāĻšā§°āĻŖ
- 1950 → Century 19 → Code 0
- 1869 → Century 18 → Code 2
- 2015 → Century 20 → Code 6
Definition : Century Code is a fixed number given to the first two digits of a year to find the day. Century Code āĻšā§āĻā§ āĻŦāĻā§°ā§° āĻĒā§ā§°āĻĨāĻŽ āĻĻā§āĻāĻž āĻ¸āĻāĻā§āĻ¯āĻžā§° āĻŦāĻžāĻŦā§ āĻ¨āĻŋā§°ā§āĻĻāĻŋāĻˇā§āĻ āĻā§°āĻž āĻāĻāĻž āĻ¸āĻāĻā§āĻ¯āĻž, āĻ¯āĻŋāĻ¯āĻŧā§ āĻĻāĻŋāĻ¨ āĻāĻŖāĻ¨āĻž āĻ¸āĻšāĻ āĻā§°ā§āĨ¤
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Day Codes (āĻĻāĻŋāĻ¨ā§° āĻ’āĻĄ)
- Sunday → 0 : āĻĻā§āĻāĻŦāĻžā§° → 0 , Monday → 1 : āĻ¸ā§āĻŽāĻŦāĻžā§° → 1 , Tuesday → 2 : āĻŽāĻāĻ˛āĻŦāĻžā§° → 2 , Wednesday → 3 : āĻŦā§āĻ§āĻŦāĻžā§° → 3 , Thursday → 4 : āĻŦā§āĻšāĻ¸ā§āĻĒāĻ¤āĻŋāĻŦāĻžā§° → 4 , Friday → 5 : āĻļā§āĻā§ā§°āĻŦāĻžā§° → 5 , Saturday → 6 : āĻļāĻ¨āĻŋāĻŦāĻžā§° → 6
Century Codes (āĻļāĻ¤āĻŋāĻāĻžā§° āĻ’āĻĄ)
- 1600 → 6, 1700 → 4, 1800 → 2, 1900 → 0, 2000 → 6, 2100 → 4
Note / āĻā§āĻāĻž: Century Code āĻŽāĻžāĻ¨ā§ āĻŦāĻā§°ā§° āĻĒā§ā§°āĻĨāĻŽ āĻĻā§āĻāĻž āĻ¸āĻāĻā§āĻ¯āĻž (16, 17, 18, 19, 20…).
Formula (āĻ¸ā§āĻ¤ā§ā§°) : Date + Month Code + Century Code + Last Two Digits of Year + Leap Years = Total
āĻ¤āĻžā§° āĻĒāĻžāĻāĻ¤, Total ÷ 7 → Remainder (āĻ ā§ąāĻļāĻŋāĻˇā§āĻ)
Remainder = Day Code = Day
Q1. What day was on 26 January 1950 ? ā§¨ā§Ŧ āĻāĻžāĻ¨ā§ā§ąāĻžā§°ā§ ā§§ā§¯ā§Ģā§Ļ āĻā§āĻ¨āĻĻāĻŋāĻ¨ āĻāĻāĻŋāĻ˛ ?
Soln
- Date = 26
- Month Code (January) = 0
- Century Code (1900) = 0
- Last two digits of year = 50
- Leap years till 1950 = 12
Total = 26 + 0 + 0 + 50 + 12 = 88 ÷ 7 = 12 remainder 4
Day Code 4 = Thursday
Ans / āĻāĻ¤ā§āĻ¤ā§°: 26 January 1950 was Thursday : ā§¨ā§Ŧ āĻāĻžāĻ¨ā§ā§ąāĻžā§°ā§ ā§§ā§¯ā§Ģā§Ļ āĻŦā§āĻšāĻ¸ā§āĻĒāĻ¤āĻŋāĻŦāĻžā§° āĻāĻāĻŋāĻ˛
Q2. What day was on 20 October 1869? ā§¨ā§Ļ āĻ āĻā§āĻā§āĻŦā§° ā§§ā§Žā§Ŧā§¯ āĻā§āĻ¨āĻĻāĻŋāĻ¨ āĻāĻāĻŋāĻ˛ ?
Soln
- Date = 20
- Month Code (October) = 0
- Century Code (1800) = 2
- Last two digits of year = 69
- Leap years till 1869 = 17
Total = 20 + 0 + 2 + 69 + 17 = 108 ÷ 7 = 15 remainder 3
Day Code 3 = Wednesday
Ans / āĻāĻ¤ā§āĻ¤ā§°: 20 October 1869 was Wednesday : ā§¨ā§Ļ āĻ āĻā§āĻā§āĻŦā§° ā§§ā§Žā§Ŧā§¯ āĻŦā§āĻ§āĻŦāĻžā§° āĻāĻāĻŋāĻ˛
Exam Tip / āĻĒā§°ā§āĻā§āĻˇāĻžā§° āĻāĻŋāĻĒāĻ
- Always remember Day Codes + Century Codes
- Divide by 7 and use remainder only
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Calendar MCQ Practice (Day–Date)
1. Century Code of the year 1950 is - 1950 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 2 | b) 4 | c) 0 | d) 6
Ans: c) 0
Explanation: 1950 → first two digits = 19 → Century code of 19 = 0
2. Century Code of the year 1869 is - 1869 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 6 | b) 2 | c) 4 | d) 0
Ans: b) 2
Explanation: 18 → Century code = 2
3. Century Code of the year 2005 is - 2005 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 0 | b) 2 | c) 4 | d) 6
Ans: d) 6
Explanation: 20 → Century code = 6
4. Which century has Century Code = 4 ? āĻā§āĻ¨ āĻļāĻ¤āĻŋāĻāĻžā§° Century Code = 4 ?
a) 1600 | b) 1700 | c) 1800 | d) 1900
Ans: b) 1700
Explanation: 17 → Century code = 4
5. Century Code of 21st century is - ā§¨ā§§āĻļāĻ¤āĻŋāĻāĻžā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 6 | b) 2 | c) 4 | d) 0
Ans: c) 4
Explanation: 21 → Century code = 4
6. In Day–Date calculation, Century Code depends on - Day–Date āĻāĻŖāĻ¨āĻžāĻ¤ Century Code āĻāĻŋāĻšā§° āĻāĻĒā§°āĻ¤ āĻ¨āĻŋā§°ā§āĻā§° āĻā§°ā§ ?
a) Month | b) Date | c) Last two digits | d) First two digits
Ans: d) First two digits
Explanation: Century code = year’s first two digits
7. Century Code of the year 1742 is - 1742 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 6 | b) 4 | c) 2 | d) 0
Ans: b) 4
Explanation: 17 → Century code = 4
8. Century Code of 1800 is - 1800 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 0 | b) 2 | c) 4 | d) 6
Ans: b) 2
Explanation: 18 → Century code = 2
9. Which is the correct Century Code sequence ? āĻ¤āĻ˛ā§° āĻā§āĻ¨āĻā§ Century Code āĻ¸āĻ āĻŋāĻ ?
a) 16→4, 17→6, 18→0 b) 16→6, 17→4, 18→2
c) 16→2, 17→0, 18→4 d) 16→0, 17→2, 18→6
Ans: b) 16→6, 17→4, 18→2
10. Century Code of 1900 is - 1900 āĻāĻ¨ā§° Century Code āĻāĻŋāĻŽāĻžāĻ¨ ?
a) 6 | b) 4 | c) 2 | d) 0
Ans: d) 0
Explanation: 19 → Century code = 0