Be a Human Calendar
July 19, 2007 – 11:49 pmThis article will enable you to demonstrate to your friends an amazing ability of memory.
It will help you improve your memory. On average, people’s brains weigh the same amount, yet some people are better than others in their skills of recollection. It’s not about “having more brains”, but in how the brain is used and trained. You can train your memory, just as an athlete trains their muscles.
The Incredible Human Calendar
Calculate the name of the day for any date for any year.
For our example, we will use today’s date, July 19, 2007.
Step 1
You will need to begin by learning a 12 digit number:
733614625735
Each of these digits corresponds to a month in the year 2007:
Jan=7 Feb=3 Mar=3 April=6 May=1 Jun=4 Jul=6 Aug=2 Sep=5 Oct=7 Nov=3 Dec=5
It will be easier to remember this long number if you look at it in groups of 3:
733-614-625-735
Step 2
Compute a total based off of the following formula:
Digit for the month + Date number = Total
From the Total, remove the number 7 as many times as you can (e.g. 8 becomes 1, 16 becomes 2) This is also known as modulo in arithmetic. 16 modulo 7 is 2 because the remainder of 16 divided by 7 is 2. Another example: 29 modulo 7 is 1.
This result represents the day name, with Monday being 1, Tuesday being 2, etc…
So for our example of Jul 19, 2007:
6 (our digit for July from our reference number) + 19 = 25
25 modulo 7 is 4.
Monday=1, Tuesday=2, Wednesday=3, Thursday=4, so our day is Thursday.
Now you know how to calculate the day of any date in the year 2007.
In a future post, I will explain how to extend this technique for other years.