Hello students! Welcome to DILR Concept 6

Concept name:– Calendar

Concept explanation: Simple Questions like day of week on particular date or at a particular duration from current time is asked. One needs to have the concept that days gets repeated in 7 days and find out day of week accordingly

Sample set: Read the information given below and answer the questions that follows:

1. Which day of week is July 21,1854?
2. If the 3rd of September 1654 is a Monday, what day of the week is 3rd of September 1854?

Solutions

1. Here we first assume that 01/01/01 is a Monday. With passage of 400 years, the same day repeats. Or we can say number of odd days after 400 years is 0. So for 1600 years, number of odd days =0. Every 100 years gives us 5 odd years. So 1600-1800 gives 10 odd days. One single year gives 1 odd day and leap year gives 2 odd day. So from 1800-1853, 53 odd days + 13 odd days for leap year = 66 odd days. So odd days beginning of 1854 =5+5+66=76=6(70-6).  Now from Jan to June no of odd days goes like (3+0+3+2+3+2)=13  Total odd days = 13+6=19=5. Now adding remaining 21 days, no of odd days= 21+5= 26 =5 odd days. So it is a Friday
2. In 200 years, there will be 5+5=10 odd days = 3 odd days. So it will be Thursday

Level of difficulty: Easy

Hope you understood solving questions on Calendars

Happy learning!

Rahul Sir

CAT Coach

Quora profile: https://www.quora.com/profile/Rahul-Anand-51