Calendar Trick: Calculate Day of Week from Date

Have you ever wondered how to quickly calculate the day of the week for any given date? This handy calendar trick uses a simple mental math technique that can help you impress your friends or just make your life a little bit easier. Let's dive in!

The Code

The trick relies on assigning numerical values to each month and each day of the week:

Month	Code
January	1
February	4
March	4
April	0
May	2
June	5
July	0
August	3
September	6
October	1
November	4
December	6

Day	Code
Sunday	0
Monday	1
Tuesday	2
Wednesday	3
Thursday	4
Friday	5
Saturday	6

The Steps

1. Identify the date you want to find the day of the week for. For example, let's say we want to find the day of the week for August 15th, 2023.
2. Extract the last two digits of the year. In our example, that would be 23.
3. Divide the year's last two digits by 4 and discard any remainder. 23 divided by 4 is 5 with a remainder of 3, so we keep 5.
4. Look up the month code from the table above. August's code is 3.
5. Add the day of the month to the values from steps 2, 3, and 4. 23 + 5 + 3 + 15 = 46
6. Divide the sum by 7 and keep the remainder. 46 divided by 7 is 6 with a remainder of 4.
7. Use the remainder as your day code and look up the corresponding day of the week from the table. A code of 4 corresponds to Thursday.

Let's Try Another Example

Let's find the day of the week for October 12th, 2024.

1. Date: October 12th, 2024
2. Last two digits of the year: 24
3. 24 divided by 4: 6
4. Month code for October: 1
5. Sum: 24 + 6 + 1 + 12 = 43
6. 43 divided by 7: 6 with a remainder of 1
7. Day code: 1 corresponds to Monday

So, October 12th, 2024 falls on a Monday.

Tips and Tricks

• Practice makes perfect. The more you use this trick, the faster you'll become at calculating days of the week.
• Memorize the month and day codes. This will make the calculation much faster.
• Use this trick for any date, past or future. Just make sure you use the correct year and month codes.

This calendar trick is a fun and easy way to impress your friends or just make your life a little bit easier. Give it a try and see how quickly you can calculate the day of the week for any given date!