Find Day / Month ?


Main Rule / āĻŽā§‚āϞ āύāĻŋāϝāĻŧāĻŽ


Day after N days = Remainder when N is divided by 7 {N āĻĻāĻŋāύ āĻĒāĻŋāϛ⧰ āĻĻāĻŋāύ = N ÷ 7 ā§° remainder (R)}


Formula / āϏ⧂āĻ¤ā§ā§°: Required Day = Given Day + (N mod 7) (āĻĒā§ā§°āϝāĻŧā§‹āϜāύ⧀āϝāĻŧ āĻĻāĻŋāύ = āĻĻāĻŋāϝāĻŧāĻž āĻĻāĻŋāύ + (N ÷ 7 ā§° remainder)


Note: N mod 7 = Remainder when N is divided by 7. (N mod 7 = NāĻ• 7⧰⧇ āĻ­āĻžāĻ— āϕ⧰āĻŋāϞ⧇ āϝāĻŋ remainder (āĻ­āĻžāĻ—āĻļ⧇āώ) āĻĒā§‹ā§ąāĻž āϝāĻžāϝāĻŧāĨ¤)


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Ex 1. Today = Sunday / āφāϜāĻŋ = Sunday, After 10 days = ? / 10 āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϤ = ?


Soln


10 ÷ 7 = 1 remainder 3


R = 3


Count 3 days from Sunday / Sundayā§° āĻĒā§°āĻž 3 āĻĻāĻŋāύ āĻ—āĻŖāύāĻž āϕ⧰āĻ•:


1 → Monday, 2 → Tuesday, 3 → Wednesday


Ans / āωāĻ¤ā§āϤ⧰: Wednesday


Ex 2. Today = Sunday / āφāϜāĻŋ = Sunday After 100 days = ? / 100 āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϤ = ?


Soln


100 ÷ 7 = 14 remainder 2


R = 2


Count 2 days from Sunday / Sundayā§° āĻĒā§°āĻž 2 āĻĻāĻŋāύ āĻ—āĻŖāύāĻž āϕ⧰āĻ•:                 1 → Monday, 2 → Tuesday


Ans / āωāĻ¤ā§āϤ⧰: Tuesday


Ex 3 : Today = Sunday / āφāϜāĻŋ = Sunday After 1000 days = ? / 1000 āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϤ = ?


Soln


1000 ÷ 7 = 142 remainder 6


R = 6


Count 6 days from Sunday / Sundayā§° āĻĒā§°āĻž 6 āĻĻāĻŋāύ āĻ—āĻŖāύāĻž : Saturday


Ans / āωāĻ¤ā§āϤ⧰: Saturday


Memory Tip / āĻŽāύāϤ ā§°āĻ–āĻžā§° āωāĻĒāĻžāϝāĻŧ: Week = 7 Days / ā§§ āϏāĻĒā§āϤāĻžāĻš = ā§­ āĻĻāĻŋāύ


Just divide by 7 and use the remainder. (āĻ•ā§‡ā§ąāϞ 7⧰⧇ āĻ­āĻžāĻ— āϕ⧰āĻ• āφ⧰⧁ remainder (R) āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āϕ⧰āĻ•āĨ¤)


i. 10 → R=3 → Wednesday, ii. 100 → R=2 → Tuesday, iii. 1000 → R=6 → Saturday


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Q. 58 days ago was Tuesday. What day is today ? ā§Ģā§Ž āĻĻāĻŋāύ āφāĻ—āϤ⧇ āĻŽāĻ™āϞāĻŦāĻžā§° āφāĻ›āĻŋāϞāĨ¤ āφāϜāĻŋ āĻ•āĻŋ āĻŦāĻžā§° ?


A) Wednesday (āĻŦ⧁āϧāĻŦāĻžā§°)  B) Thursday (āĻŦ⧃āĻšāĻ¸ā§āĻĒāϤāĻŋāĻŦāĻžā§°)  C) Sunday (āĻĻ⧇āĻ“āĻŦāĻžā§°)  D) Friday (āĻļ⧁āϕ⧁⧰āĻŦāĻžā§°)


Solution | āϏāĻŽāĻžāϧāĻžāύ

A week has 7 days. (āĻāϟāĻž āϏāĻĒā§āϤāĻžāĻšāϤ ā§­ āĻĻāĻŋāύ āĻĨāĻžāϕ⧇āĨ¤)


Find the remainder when 58 is divided by 7 (ā§Ģā§ŽāĻ• ⧭⧰⧇ āĻ­āĻžāĻ— āϕ⧰āĻŋāϞ⧇ āĻ­āĻžāĻ—āĻļ⧇āώ āωāϞāĻŋāϝāĻŧāĻžāĻ“āρ:): 58 ÷ 7 = 8 remainder () 2 


So āĻ…ā§°ā§āĻĨāĻžā§Ž,, 58 days = 56 days + 2 days. (ā§Ģā§Ž āĻĻāĻŋāύ = ā§Ģā§Ŧ āĻĻāĻŋāύ + ⧍ āĻĻāĻŋāύ)


56 days = 8 weeks (same day) [ā§Ģā§Ŧ āĻĻāĻŋāύ = ā§ŽāϟāĻž āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āϏāĻĒā§āϤāĻžāĻš (āĻāϕ⧇āχ āĻŦāĻžā§° āĻĨāĻžāĻ•āĻŋāĻŦ)]



  • 2 extra days ahead (āĻ…āϤāĻŋā§°āĻŋāĻ•ā§āϤ ⧍ āĻĻāĻŋāύ āφāĻ—āĻŦāĻžāĻĸāĻŧāĻŋāĻŦ āϞāĻžāĻ—āĻŋāĻŦ)


Starting from Tuesday: āĻŽāĻ™āϞāĻŦāĻžā§°ā§° āĻĒā§°āĻž āĻ—āĻŖāύāĻž āϕ⧰āĻ•:



  • Wednesday = 1 day : āĻŦ⧁āϧāĻŦāĻžā§° = ā§§ āĻĻāĻŋāύ

  • Thursday = 2 days : āĻŦ⧃āĻšāĻ¸ā§āĻĒāϤāĻŋāĻŦāĻžā§° = ⧍ āĻĻāĻŋāύ


Ans: B) Thursday (āĻŦ⧃āĻšāĻ¸ā§āĻĒāϤāĻŋāĻŦāĻžā§°)


Trick | āĻŸā§ā§°āĻŋāĻ•

  • Divide the number of days by 7.

  • Ignore the quotient and use only the remainder.

  • Move forward by the remainder.


58 ÷ 7 = remainder 2


Tuesday + 2 = Thursday


Ans: B) Thursday (āĻŦ⧃āĻšāĻ¸ā§āĻĒāϤāĻŋāĻŦāĻžā§°)


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Q. 45 days later will be Saturday. What day is today ? ā§Ēā§Ģ āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϤ āĻļāύāĻŋāĻŦāĻžā§° āĻš'āĻŦāĨ¤ āφāϜāĻŋ āĻ•āĻŋ āĻŦāĻžā§° ?

















A) Thursday (āĻŦ⧃āĻšāĻ¸ā§āĻĒāϤāĻŋāĻŦāĻžā§°)  B) Wednesday (āĻŦ⧁āϧāĻŦāĻžā§°)  C) Tuesday (āĻŽāĻ™āϞāĻŦāĻžā§°)  D) Monday (āϏ⧋āĻŽāĻŦāĻžā§°)


Solution | āϏāĻŽāĻžāϧāĻžāύ

A week has 7 days. (āĻāϟāĻž āϏāĻĒā§āϤāĻžāĻšāϤ ā§­ āĻĻāĻŋāύ āĻĨāĻžāϕ⧇āĨ¤)


Find the remainder when 45 is divided by 7: 45 ÷ 7 = 6 remainder 3


So,



  • 45 days = 42 days + 3 days

  • 42 days = 6 weeks (same day)

  • 3 extra days


Since 45 days later is Saturday, count 3 days backward from Saturday: āϝāĻŋāĻšā§‡āϤ⧁ ā§Ēā§Ģ āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϤ āĻļāύāĻŋāĻŦāĻžā§° āĻš'āĻŦ, āϏ⧇āϝāĻŧ⧇āĻšā§‡ āĻļāύāĻŋāĻŦāĻžā§°ā§° āĻĒā§°āĻž ā§Š āĻĻāĻŋāύ āĻĒāĻŋāĻ›āϞ⧈ (āωāĻ˛ā§āϟāĻž āĻĻāĻŋāĻļ⧇) āĻ—āĻŖāύāĻž āϕ⧰āĻ•:



  • Saturday → Friday = 1 day

  • Friday → Thursday = 2 days

  • Thursday → Wednesday = 3 days


Ans: B) Wednesday (āĻŦ⧁āϧāĻŦāĻžā§°)


Trick | āĻŸā§ā§°āĻŋāĻ•

  • Divide the number of days by 7. (āĻĻāĻŋāύ⧰ āϏāĻ‚āĻ–ā§āϝāĻžāĻ• ⧭⧰⧇ āĻ­āĻžāĻ— āϕ⧰āĻ•āĨ¤)

  • Take only the remainder. (āĻ•ā§‡ā§ąāϞ āĻ­āĻžāĻ—āĻļ⧇āώāĻŸā§‹ āϞāĻ“āĻ•āĨ¤)

  • If the question says "after" (later) and asks today, move backward by the remainder. (āϝāĻĻāĻŋ āĻĒā§ā§°āĻļā§āύāϤ "āĻĒāĻŋāĻ›āϤ (after/later)" āĻŦ⧁āϞāĻŋ āĻ•ā§ˆ āφāϜāĻŋā§° āĻŦāĻžā§° āϏ⧋āϧ⧇, āϤ⧇āĻ¨ā§āϤ⧇ āĻ­āĻžāĻ—āĻļ⧇āώ āĻ…āύ⧁āϏ⧰āĻŋ āωāĻ˛ā§āϟāĻž āĻĻāĻŋāĻļ⧇ (backward) āĻ—āĻŖāύāĻž āϕ⧰āĻ•āĨ¤)


                    45 ÷ 7 = 6 remainder 3


Saturday − 3 days = Wednesday


Ans: B) Wednesday (āĻŦ⧁āϧāĻŦāĻžā§°)


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Q. What day will be 15 January 2050 ?






Options: A) Monday  B) Tuesday  C) Thursday  D) Saturday


Formula: (Date + Month Code + Century Code + Year + Leap Years) ÷ 7


Given:

  • Date = 15

  • January Month Code = 0

  • Century Code (2000s) = 6

  • Year = 50

  • Leap Years = 12


15 + 0 + 6 + 50 + 12 = 83

 83 ÷ 7 = Remainder 6

Day Code: 6 = Saturday


Ans: D) Saturday


Day - Code Trick : 0 = Sunday | 1 = Monday | 2 = Tuesday | 3 = Wednesday | 4 = Thursday | 5 = Friday | 6 = Saturday


Therefore: 15 January 2050 = Saturday


Trick


January = 0, 2000 Century = 6


15 + 0 + 6 + 50 + 12 = 83


83 → Remainder 6 → Saturday


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Q. What day was 26 January 1950 ?


Options: A) Monday  B) Thursday  C) Friday  D) Sunday


Trick


Formula: (Date + Month Code + Century Code + Year + Leap Years) ÷ 7


For 26 January 1950: Date = 26, January Code = 0, 1900 Century Code = 0, Last two digits = 50, Leap Years = 12


26 + 0 + 0 + 50 + 12 = 88


88 ÷ 7 ⇒ Remainder 4


Using the code: 0 = Sunday | 1 = Monday | 2 = Tuesday | 3 = Wednesday | 4 = Thursday | 5 = Friday | 6 = Saturday


Therefore:






















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