Aptitude Topics
Day Calculations
By counting odd days from a known reference point, you can accurately determine the day of the week for any date.
Fundamental Principles
Reference Date
A known date (like Jan 1, 2001, being a Monday) used as a base for calculations.
Essential Formulation Tips
- Sum up odd days for centuries, years, months, and days.
- Add these sums and find the final remainder when divided by 7.
Shortcut Execution Techniques
- Remember the Century code: 100 years = 5 odd days, 200 years = 3 odd days, 300 years = 1 odd day, 400 years = 0 odd days.
Contextual Inquiries (FAQs)
Q: Why use January 1, 2001, as a reference?
A: It is a convenient modern reference point where Jan 1, 2001, was a Monday.
Example Breakdown: Determining a Day
Demonstrates day shifting.Problem QueryWhat day was Jan 1, 2002?
Step-By-Step Solution Path
Jan 1, 2001 was a Monday.
2001 is an ordinary year (1 odd day).
Monday + 1 odd day = Tuesday.
Jan 1, 2002 was a Tuesday.
Analytical Hint: Count total odd days from your reference.
Day Calculation Practice
Practice determining the day for various dates.
Q1. If Jan 1, 2001 was Monday, what day was Jan 1, 2003?