Interesting patterns in calendars.
Determine the last day of February
Even months: 4th April, 6th June, 8th August, 10th October and 12th December will all fall on the same day.
Odd months: May, July, September and November. Months: 5, 7, 9 and 11.
• for the 9th month, the 5th falls on the same day
• for the 5th month, the 9th falls on the same day
• for the 7th month, the 11th falls on the same day
• for the 11th month, the 7th falls on the same day
Use the following mnemonic phrase to remember the pattern:
I work 9-5 at the 7-11
“Nine to five” is a common working day, and 7-Eleven is a chain of convenience stores.
The 7th of March, exactly one week after the last day of February, no matter whether it’s the 28th or 29th, also falls on the same day of the week.
Finally, we have to be able to do January: It’s January 3rd three years out of four, the non-leap years. It’s January 4th only in the fourth year, the years divisible by 4.
Once you know the day of the week for the 28/29th of February you can easily mentally calculate the day of any date in that year. You simply add, subtract using multiples of 7. With a little practice it becomes easy to mentally picture the month and see the day that a date falls on. I suspect that children with autism that do the calendar trick probably use a similar approach.
Interactive Calendar : http://www.apples4theteacher.com/calendar.html
Chris.