How to Calculate in Your Head the Month when You Know the Rest of the Date

Step-by-Step Guide

1. 1

   Step 1: Subtract from the day the largest multiple of 7 contained in it (the multiples of 7 are 0

   and hold this number until step
   4.
2. 2

   Step 2: Subtract from the last two digits of year the largest multiple of 28 contained in it (note: the multiples of 28 are 00

   Divide the result by 4 and ignore any decimal.
   
   Add these two numbers together. , (This is the value for the year.) , This is the value for the Day and Year. , If that value is less than the value for the Day and the Year (step 4) add
   7. , Look up the result in the Month Table (to the right of step 1) for all months that have that value (but if the year is a leap year, you must subtract 1 from the values shown in the table for January and February, leaving them at 6 and 2, respectively).
3. 3

   Step 3: 56 and 84).

4. 4

   Step 4: Add to the result in step 2 the value for the century from the Century Table to the right of step 1.

5. 5

   Step 5: Add together the results from steps 1 and 3 and then subtract from the largest multiple of 7 contained in it (if the number is 7 or greater

6. 6

   Step 6: that is) for a number between 0 and 6.

7. 7

   Step 7: Look up the value for the known Day of the Week in the Day of the Week Table.

8. 8

   Step 8: Subtract from the above result the value for the Day and Year from step 3.

Detailed Guide

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