0
0

Yearly Day Shift

Introduction

Yearly Day Shift पैटर्न बताता है कि जब आप किसी तारीख से ठीक एक साल आगे या पीछे जाते हैं, तो उसका weekday कैसे बदलता है। यह कैलेंडर reasoning का आधार है - लगभग हर date-आधारित प्रश्न (next-year weekday, repeating calendars, multi-year shifts) में इसका उपयोग होता है।

Pattern: Yearly Day Shift

Pattern

अगले वर्ष में वही तारीख किस weekday पर आएगी, यह उस वर्ष द्वारा योगदान किए गए odd days पर निर्भर करता है जिसे आपने पार किया है:

  • अगर पार किया गया वर्ष ordinary year है → यह +1 odd day देता है, इसलिए वही तारीख अगले साल +1 weekday आगे होगी।
  • अगर पार किया गया वर्ष leap year है → यह +2 odd days देता है, इसलिए वही तारीख अगले साल +2 weekdays आगे होगी।
  • पीछे जाते समय (backward) ordinary → -1 और leap → -2 day का शिफ्ट लागू करें।

Step-by-Step Example

Question

यदि 1st January 2022 Saturday है, तो 1st January 2023 कौन सा दिन होगा?

Solution

  1. Step 1: जिस वर्ष को पार कर रहे हैं, उसका प्रकार पहचानें

    हम 1 Jan 2022 → 1 Jan 2023 जा रहे हैं। यानी पार किया गया वर्ष 2022 है। 2022 एक ordinary year है (4 से divisible नहीं)।

  2. Step 2: Odd-day योगदान

    Ordinary year → +1 odd day।

  3. Step 3: Weekday शिफ्ट लागू करें

    Base weekday = Saturday. +1 जोड़ें → Sunday.

  4. Final Answer:

    Sunday

  5. Quick Check:

    Ordinary year shift = +1 → Saturday → Sunday ✅

Quick Variations

1. Backward shift: पिछले वर्ष की same date निकालते समय ordinary → -1, leap → -2 लागू करें।

2. Leap day पार करते समय: यदि leap वर्ष से पहले की तारीख से अगले वर्ष वही तारीख ले रहे हैं, तो +2 शिफ्ट leap year से आता है।

3. Multi-year shifts: n वर्षों के लिए ordinary = 1, leap = 2 जोड़ें, फिर mod 7 करके net shift निकालें।

Trick to Always Use

  • Step 1 → पार किया गया वर्ष leap (2) है या ordinary (1), पहले तय करें।
  • Step 2 → आगे जाते समय odd days जोड़ें; पीछे जाते समय घटाएँ।
  • Step 3 → अंतिम योग mod 7 करें और weekday शिफ्ट करें।

Summary

Summary

  • Ordinary year पार करने पर वही तारीख अगले वर्ष +1 weekday आगे होती है।
  • Leap year पार करने पर वही तारीख अगले वर्ष +2 weekdays आगे होती है।
  • Backward move में इन्हीं मानों को घटाएँ। Multi-year समाधान में सभी वर्षों के odd days जोड़कर mod 7 करें।
  • Repeating-calendar और long-range date calculations के लिए यह नियम आधारभूत है।

याद रखने का उदाहरण:
1 Jan 2020 (leap year) = Wednesday → 1 Jan 2021 = Friday (+2 shift).

Practice

(1/5)
1. If 1st January 2021 was Friday, what day was 1st January 2022?
easy
A. Saturday
B. Sunday
C. Thursday
D. Monday

Solution

  1. Step 1: Identify the year crossed

    We move from 1 Jan 2021 → 1 Jan 2022, so the year crossed is 2021.

  2. Step 2: Determine if that year is leap or ordinary

    2021 is an ordinary year (not divisible by 4) → contributes +1 odd day.

  3. Step 3: Apply the shift to the weekday

    Base day = Friday. Friday + 1 = Saturday.

  4. Final Answer:

    Saturday → Option A

  5. Quick Check:

    Ordinary year → +1 day shift → Friday → Saturday ✅
Hint: Crossing an ordinary year → add +1 to the weekday.
Common Mistakes: Forgetting to check leap status of the year being crossed.
2. If 15th March 2019 was Friday, what day was 15th March 2020?
easy
A. Friday
B. Saturday
C. Sunday
D. Thursday

Solution

  1. Step 1: Identify the date range

    We move from 15 Mar 2019 → 15 Mar 2020.

  2. Step 2: Check whether Feb 29 occurs between these dates

    Since the date is after February, the leap day of 2020 (29 Feb) lies between the two dates. So the interval contains 366 days → 2 odd days.

  3. Step 3: Apply the shift

    Base weekday = Friday. Friday + 2 = Sunday.

  4. Final Answer:

    Sunday → Option C

  5. Quick Check:

    Target year 2020 is leap and the date is after Feb → +2 odd days → Friday → Sunday ✅
Hint: For dates after February, if the target year is leap, Feb 29 is included → +2 shift.
Common Mistakes: Using only the crossed-year method without checking that Feb 29 lies between the dates.
3. If 10th October 2015 was Saturday, what day was 10th October 2016?
easy
A. Friday
B. Saturday
C. Sunday
D. Monday

Solution

  1. Step 1: Identify the date range

    We move from 10 Oct 2015 → 10 Oct 2016.

  2. Step 2: Check leap-day inclusion

    The target year 2016 is a leap year, and the date (10 Oct) is after February. Hence Feb 29, 2016 lies between these dates → interval = 366 days → 2 odd days.

  3. Step 3: Apply the shift

    Base day = Saturday. Saturday + 2 = Monday.

  4. Final Answer:

    Monday → Option D

  5. Quick Check:

    Leap-day included → +2 → Saturday → Monday ✅
Hint: For dates after February, crossing into a leap year always includes Feb 29 → +2 shift.
Common Mistakes: Checking only the previous year's type instead of determining whether Feb 29 lies between the dates.
4. If 1st March 2019 was Friday, what day was 1st March 2021?
medium
A. Sunday
B. Tuesday
C. Wednesday
D. Monday

Solution

  1. Step 1: List years crossed

    From 1 Mar 2019 → 1 Mar 2021 we cross years 2019 and 2020.

  2. Step 2: Sum odd-day contributions

    2019 = ordinary → +1; 2020 = leap → +2. Total shift = 1 + 2 = +3 odd days.

  3. Step 3: Apply shift to weekday

    Base day = Friday. Friday + 3 = Monday.

  4. Final Answer:

    Monday → Option D

  5. Quick Check:

    Sum of odd days = 3 → Friday → Monday ✅
Hint: For multi-year moves, add each year’s contribution (ordinary =1, leap =2) then reduce mod 7.
Common Mistakes: Treating the 2-year move as two ordinary years (would give +2 instead of +3).
5. If 5th July 2016 was Tuesday, what day was 5th July 2020?
medium
A. Sunday
B. Monday
C. Saturday
D. Friday

Solution

  1. Step 1: List years crossed

    From 5 Jul 2016 → 5 Jul 2020 we cross 2016, 2017, 2018, 2019.

  2. Step 2: Determine odd-day contributions

    2016 = leap → +2; 2017 = ordinary → +1; 2018 = ordinary → +1; 2019 = ordinary → +1. Total = 2 + 1 + 1 + 1 = 5 odd days.

  3. Step 3: Apply shift

    Base day = Tuesday. Tuesday + 5 = Sunday.

  4. Final Answer:

    Sunday → Option A

  5. Quick Check:

    Total odd days 5 → Tuesday → Sunday ✅
Hint: Include the leap-year contribution when it appears in the crossed years (2016 here).
Common Mistakes: Ignoring the +2 from crossing a leap year and using +1 instead.

Mock Test

Ready for a challenge?

Take a 10-minute AI-powered test with 10 questions (Easy-Medium-Hard mix) and get instant SWOT analysis of your performance!

10 Questions
5 Minutes