The Doomsday Algorithm - Numberphile

Numberphile2 minutes read

The Doomsday method allows determining the day of the week for any date by using special dates and adjusting non-special dates accordingly. Special dates and key years are memorized to simplify the calculation process, with a KiwiCo subscription box project mentioned as a hands-on learning experience for all ages.

Insights

  • The calendar trick involves memorizing special dates like 4th of April, 6th of June, 8th of August, 10th of October, and 12th of December, which share the same day of the week, simplifying the determination of the day for any given date.
  • Utilizing the Doomsday method includes memorizing key dates and years, converting days of the week into numbers, and adjusting non-special dates by finding the nearest special date, culminating in a systematic approach to calculating the day of the week for historical or future dates.

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Recent questions

  • How can I determine the day of the week for any date?

    To determine the day of the week for any given date, you can use the calendar trick. By memorizing special dates like 4th of April, 6th of June, 8th of August, 10th of October, and 12th of December, you can apply the Doomsday method. Special dates like 9th of the 5th, 5th of the 9th, 7th of the 11th, and 11th of the 7th share the same day of the week. For non-special dates, find the nearest special date and adjust by adding or subtracting days. Converting days of the week into numbers simplifies the calculation process, and memorizing key years like 0, 28, 56, and 84 helps in determining the day of the week for dates in the past or future.

  • What are the special dates for January, February, and March?

    Special dates for January, February, and March are the 3rd or 4th, last day of February, and 14th of March (Pi day) respectively. Knowing the day of the week for Pi day can help determine all special dates for the year. By applying the Doomsday method and memorizing key dates, you can easily calculate the day of the week for these special dates.

  • How do I calculate the Doomsday for a future year?

    To calculate the Doomsday for a future year, add the year and leap years to the Doomsday of 2000. By using the Doomsday method and converting days of the week into numbers, you can simplify the calculation process and determine the day of the week for any date in the future.

  • What is the significance of the 18th of June in the Doomsday method?

    The 18th of June was used as an example in the Doomsday method, starting with the calculation based on the 6th of June as a reference point. By adding 12 days, the final result was 5, which corresponds to a Friday. This demonstrates how the Doomsday method can be applied to determine the day of the week for any date.

  • How can I engage in hands-on learning experiences related to calendars?

    You can engage in hands-on learning experiences related to calendars through a perpetual calendar project offered by KiwiCo subscription boxes. These kits are educational and suitable for various age groups, providing a fun way to learn about calendars and dates. By visiting KiwiCo.com/Numberphile, you can access a 50% discount on the first box, encouraging participation in interactive and educational activities.

Related videos

Summary

00:00

Mastering the Calendar Trick for Any Date

  • The calendar trick allows determining the day of the week for any given date.
  • A book of calendars from 1800 to 2100 is used for this trick.
  • The Doomsday method involves memorizing special dates like 4th of April, 6th of June, 8th of August, 10th of October, and 12th of December.
  • Special dates like 9th of the 5th, 5th of the 9th, 7th of the 11th, and 11th of the 7th share the same day of the week.
  • Special dates for January, February, and March are the 3rd or 4th, last day of February, and 14th of March (Pi day) respectively.
  • Adjusting non-special dates involves finding the nearest special date and adding or subtracting days.
  • Knowing the day of the week for Pi day helps determine all special dates for the year.
  • To calculate Doomsday for a future year, add the year and leap years to the Doomsday of 2000.
  • Converting days of the week into numbers simplifies the calculation process.
  • Memorizing key years like 0, 28, 56, and 84 helps in quickly determining the day of the week for dates in the past or future.

12:16

"June 18: Doomsday Method & KiwiCo Project"

  • The Doomsday method was applied on the 18th of June, starting with the calculation based on the 6th of June as a reference point, adding 12 days to reach the final result of 5, which corresponds to a Friday.
  • A perpetual calendar project involving a KiwiCo subscription box was highlighted, emphasizing the educational value of the kits for various age groups, offering a 50% discount on the first box through KiwiCo.com/Numberphile, encouraging engagement in hands-on learning experiences.
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