Question

What is the 100th day of the calendar year? (Start at January 1st)

Answer 1

The 100th day of a common year is March 10th, while in a leap year, it is March 9th. This can be calculated by adding the days of the months sequentially from January 1st. The leap year rule from the Gregorian calendar reform does not change this for most years.

Step-by-step explanation:

To calculate the 100th day of the calendar year, starting with January 1st as the first day, we use simple arithmetic. We add 99 to January 1st because January 1st is day 1, and we're looking for the 100th day. Here are the steps:

1. Count the total number of days in January (31 days).
2. Add the total number of days in February (28 days for a common year, 29 for a leap year).
3. If after February there are still days left to reach 100, continue adding the days of the following months until you reach the total.

For a common year:

• January: 31 days
• February: 28 days
• March would be the next month. By the end of February, we have accounted for 59 days (31 + 28). Therefore, March 10th would be the 100th day (41 days after February 28th).

In a leap year, February has 29 days, so the 100th day would be March 9th.

Remember, the Gregorian calendar reform changed the rule for leap year, with century years only being a leap year if they are divisible by 400. Still, this doesn't affect the calculation of the 100th day for most years.

Answer 2

The next leap day is actually on February 29th, 2016 (this year).
This means that we have to add an extra day at the end of February every 4 years.
As you may know, the 28th is usually the last day of February, but due to the leap day, we add an extra day to make the overall days of one year 366 instead of the usual 365.

For this year (2016) the 100th day of the year is on April 9th.
On a 365 days calendar, the 100th day of the year is on April 10th.