To Find out the Day of the Week of any Day

You need to remember
  • a magic number per month, and
  • a magic number per century
    • (although for the 1900's the magic number is 0.)
Now add together
  • the date,
  • the year,
  • the year divided by 4,
  • the magic number for the month,
  • the magic number for the century,
and there might be a correction.
Magic Month No. *
January 1 4 4 March
April 0 2 5 June
July 0 3 6 September
October 1 4 6 December
Magic Century No.**
1700 - 1799 4
1800 - 1899 2
1900 - 1999 0
2000 - 2099 6
2100 - 2199 4


Example

Let's do 29th April, 1951.

Add together:

Day 29
Year (last 2 digits) 51
of year (forget any remainder) 12
Magic Month Number* 0
Magic Century Number** 0
(-1 if Jan/Feb of Leap Year) 0
TOTAL B = 92

Now divide your total by 7, and keep the remainder.

Our total was 92, which is a multiple of 7 with 1 remainder.
Hence 29th April 1951 was a Sunday

Remainder Day of the Week
1
Sunday
2
Monday
3
Tuesday
4
Wednesday
5
Thursday
6
Friday
0
Saturday


Notes:


This is one of the many Enrichment tasks on this site.
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