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# Doomsday Calculator

This calculator gives a quick lesson on how to calculate the weekday of any given date without the help of calculators, computers, or calendars is using the doomsday algorithm.

## Enter the date to calculate

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This result is based on the Gregorian calendar and might differ from the actual weekday in some countries.

### 1) How many times does the number 12 fit as a whole into the two last digits of the year number?

Last two year digits: 83

12 fits in 6 time(s)

### 2) What is the difference between the two last digits of the year number and the product of the multiples of 12 from calculation 1 (remainder)?

Last two year digits: 83

12 times Step 1: 12 x 6 = 72

83 - 72 = 11

### 3) How many times does the number 4 fit into the result of calculation 2?

Result from last step:11

4 fits in : 2 time(s)

### 4) What is the century's anchor day?

• 1800-1899 - Friday (5)
• 1900-1999 - Wednesday (3)
• 2000-2999 - Tuesday (2)
• 2100-2199 - Sunday (0)

### 5) Add up all the results.

6 + 11 + 2 + 3 = 22

### 6) Subtract whole multiples of 7 from the result of calculation 5.

This will result in a number between 0 and 6, which corresponds to the doomsday of the year.

22 - 7 = 15
15 - 7 = 8
8 - 7 = 1

• 0 - Sunday
• 1 - Monday
• 2 - Tuesday
• 3 - Wednesday
• 4 - Thursday
• 5 - Friday
• 6 - Saturday

### 7) Find the closest doomsday.

Note: the year specified is a leap year.

• January 34
• February 2829
• April 4
• May 9
• June 6
• July 11
• August 8
• September 5
• October 10
• November 7
• December 12

### 8) Count forward/backward from the doomsday to the specified date.

• 04 April 1983 - Monday
• 11 April 1983 - Monday
• 18 April 1983 - Monday
• 19 April 1983 - Tuesday
• 20 April 1983 - Wednesday

### Example Uses

Calculate the day of the week for: