📑 Topics on this page (Jump to Topic):
📌 1. Odd Days
| Period | Odd days |
|---|---|
| Ordinary year (365 days) | 1 |
| Leap year (366 days) | 2 |
| 100 years | 5 |
| 200 years | 3 |
| 300 years | 1 |
| 400 years | 0 |
| 31-day month | 3 |
| 30-day month | 2 |
| February (28/29) | 0 / 1 |
| Odd days | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|---|
| Day | Sun | Mon | Tue | Wed | Thu | Fri | Sat |
💡 Memory Tip: Month odd days (ordinary year): Jan 3, Feb 0, Mar 3, Apr 2, May 3, Jun 2, Jul 3, Aug 3, Sep 2, Oct 3, Nov 2, Dec 3.
📌 2. Leap Year
- Ordinary year: leap if divisible by 4.
- Century year: leap only if divisible by 400 — 2000 is leap, 1900 is not.
⚠️ Exam Traps:
- The extra leap day is 29 Feb — for a March-to-March period, look at the next year's February.
- The same date moves 1 day ahead next year (2 days if a leap February falls in between).
📌 3. Repeating Calendars
- An ordinary year's calendar usually repeats after 6 or 11 years (depends on leap years in between).
- A leap year's calendar repeats after 28 years (if no century rule interferes).
- Method: add odd days until the total is a multiple of 7 and the year type (leap/ordinary) matches.
📌 4. Practice MCQs
📝 Practice MCQs (prepared by SF Prep — not PYQs)
Q1. How many odd days are in an ordinary year? Practice
Correct answer: (B)
365 = 52 weeks + 1 day.
365 = 52 weeks + 1 day.
Q2. Which of these is not a leap year? Practice
Correct answer: (C)
1900 is a century year not divisible by 400.
1900 is a century year not divisible by 400.
Q3. If 1 January 2026 is a Thursday, what day is 1 January 2027? Practice
Correct answer: (D)
2026 is ordinary ⇒ 1 odd day ⇒ Friday.
2026 is ordinary ⇒ 1 odd day ⇒ Friday.
Q4. If 1 January 2024 was a Monday, what day was 1 January 2025? Practice
Correct answer: (A)
2024 is a leap year ⇒ 2 odd days ⇒ Monday + 2 = Wednesday.
2024 is a leap year ⇒ 2 odd days ⇒ Monday + 2 = Wednesday.
Q5. How many odd days are there in 400 years? Practice
Correct answer: (B)
400 years have 0 odd days.
400 years have 0 odd days.
Q6. How many odd days are there in 100 years? Practice
Correct answer: (C)
76 ordinary + 24 leap = 76 + 48 = 124 = 17 weeks + 5.
76 ordinary + 24 leap = 76 + 48 = 124 = 17 weeks + 5.
Q7. The 3rd of a month is a Monday. What day is the 24th of that month? Practice
Correct answer: (D)
24 − 3 = 21 = 3 weeks ⇒ same day, Monday.
24 − 3 = 21 = 3 weeks ⇒ same day, Monday.
Q8. The 5th of a month is a Friday. What day is the 25th of that month? Practice
Correct answer: (A)
25 − 5 = 20 = 2 weeks + 6 ⇒ Friday + 6 = Thursday.
25 − 5 = 20 = 2 weeks + 6 ⇒ Friday + 6 = Thursday.
Q9. What day of the week was 15 August 1947? Practice
Correct answer: (B)
1600 yrs: 0; 300 yrs: 1; 46 yrs (11 leap + 35 ordinary) = 57 → 1; in 1947 up to 15 Aug: 3+0+3+2+3+2+3+15 = 31 → 3. Total 0+1+1+3 = 5 ⇒ Friday.
1600 yrs: 0; 300 yrs: 1; 46 yrs (11 leap + 35 ordinary) = 57 → 1; in 1947 up to 15 Aug: 3+0+3+2+3+2+3+15 = 31 → 3. Total 0+1+1+3 = 5 ⇒ Friday.
Q10. In which year will the calendar of 2026 repeat exactly? Practice
Correct answer: (C)
Add odd days from 2026: 1,1,2,1,1,1,2,1,1,1,2 = 14 ⇒ 2037 (an ordinary year).
Add odd days from 2026: 1,1,2,1,1,1,2,1,1,1,2 = 14 ⇒ 2037 (an ordinary year).
Q11. In which year will the calendar of 2024 (a leap year) repeat? Practice
Correct answer: (D)
A leap year's calendar repeats after 28 years: 2024 + 28 = 2052.
A leap year's calendar repeats after 28 years: 2024 + 28 = 2052.
Q12. In an ordinary year, if 1 March is a Wednesday, what day is 1 April? Practice
Correct answer: (A)
March has 31 days ⇒ 3 odd days ⇒ Wednesday + 3 = Saturday.
March has 31 days ⇒ 3 odd days ⇒ Wednesday + 3 = Saturday.
Q13. How many weeks and extra days are in a leap year? Practice
Correct answer: (B)
366 = 52 × 7 + 2.
366 = 52 × 7 + 2.
Q14. Today is Friday. What day will it be after 100 days? Practice
Correct answer: (C)
100 = 14 × 7 + 2 ⇒ Friday + 2 = Sunday.
100 = 14 × 7 + 2 ⇒ Friday + 2 = Sunday.
Q15. If the day three days from today is Sunday, what day was yesterday? Practice
Correct answer: (D)
Today = Sunday − 3 = Thursday ⇒ yesterday was Wednesday.
Today = Sunday − 3 = Thursday ⇒ yesterday was Wednesday.
Q16. 1 January 2000 was a Saturday. What day was 1 January 2001? Practice
Correct answer: (A)
2000 is a leap year (divisible by 400) ⇒ 2 odd days ⇒ Monday.
2000 is a leap year (divisible by 400) ⇒ 2 odd days ⇒ Monday.
Q17. In an ordinary year, which two months always have the same calendar? Practice
Correct answer: (B)
Odd days Jan–Sep: 3+0+3+2+3+2+3+3+2 = 21 → 0 ⇒ October starts on January's weekday; both have 31 days.
Odd days Jan–Sep: 3+0+3+2+3+2+3+3+2 = 21 → 0 ⇒ October starts on January's weekday; both have 31 days.
Q18. On which day can the last day of a century never fall? Practice
Correct answer: (C)
Odd days for 100, 200, 300, 400 years are 5, 3, 1, 0 ⇒ Fri, Wed, Mon, Sun. Never Tue, Thu or Sat.
Odd days for 100, 200, 300, 400 years are 5, 3, 1, 0 ⇒ Fri, Wed, Mon, Sun. Never Tue, Thu or Sat.
Q19. 26 January 2026 is a Monday. What day will 26 January 2027 be? Practice
Correct answer: (D)
February 2026 (28 days) lies between ⇒ 1 odd day ⇒ Tuesday.
February 2026 (28 days) lies between ⇒ 1 odd day ⇒ Tuesday.
Q20. A 31-day month has 5 Sundays. Which day cannot be the first day of the month? Practice
Correct answer: (A)
31 days = 4 weeks + 3 days; Sunday must be among the first 3 days ⇒ the 1st is Fri, Sat or Sun. Not Monday.
31 days = 4 weeks + 3 days; Sunday must be among the first 3 days ⇒ the 1st is Fri, Sat or Sun. Not Monday.