Do you know what day of the week your birthday falls on this year? What about your anniversary or Christmas? In this episode, learn how you can tell this without a calculator from multi-award winning Guinness World Record Holder Scott Flansburg (also known as The Human Calculator®).
Nowadays, we’re reliant on our smart devices so our brains don’t get the exercise they need.
So how can you remain mentally active?
Scott Flansburg, also known as The Human Calculator®, is a multi-award winning Guinness World Record Holder. He says there is a pattern in calendars where you can calculate what day of the week any date falls on.
For 2017, memorize the following values for each month:
- January: 6
- February: 2
- March: 2
- April: 5
- May: 0
- June: 3
- July: 5
- August: 1
- September: 4
- October: 6
- November: 2
- December: 4
To figure out the day of the week any date falls on, calculate the following:
- Add the date to the value of the month above.
- If the number is greater than 7, divide the number by 7 and calculate the remainder.
- The number you get determines the day of the week, where 0 is Sunday and 6 is Saturday.
- Example 1:
- Christmas is on December 25. The value of December is 4. 25 + 4 is 29. 29 divided by 7 is 4, with a remainder of 1. Christmas is on a Monday.
- Example 2:
- Halloween is on October 31. The value of October is 6. 6 + 31 is 37. 37 divided 7 is 5, with a remainder of 2. Halloween is on a Tuesday.
- If you can memorize the values for each month, this is a great mental exercise to help keep you mentally fit as a mental athlete or ‘mathlete.’
- This is also a good way to keep track of your mental state. When we rely on our smart devices too much, we don’t notice memory lapses that can be early signs of conditions like dementia.
Our calendar is one of the foundations of society, but we don’t know what date any day of the week is on.
Upon realizing this, Scott developed his own Human Calculator Calendar. This calendar has 13 months with 28 days each, so every 1st of the month falls on the same day.
Test Yourself: What day does August 15 fall on?
You can also use this technique backwards.
- Want to know what date Thanksgiving falls on this year? Pick a number and see how close you can get!
- Example 3:
- Let’s say November 24 could be Thanksgiving. The value of November is 2. 2 + 24 is 26. 26 divide by 7 is 3 with a remainder of 5. November 24 is a Friday, so Thanksgiving is on November 23rd.
You can also use this technique in future years.
- For 2018, add 1 to the values listed above. For 2019, add 2 to the listed values above.
- This technique won’t work in 2020 since it’s a leap year, so you’ll have to tune back into the podcast!