BDAYMETHODA calendar in your head
ENFRDE

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02 · Shortcut

The year anchor

Keep the century anchor. Use the last two year digits and your 28-year shortcut to find the anchor for the whole year.

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How it works — step by step

  1. Keep the last two digits: 1981 → 81.
  2. Subtract the largest of 84, 56 or 28 that fits. If the number is below 28, subtract 0. Here: 81 − 56 = 25.
  3. Divide the reduced number by 4 and keep only the whole part: 25 ÷ 4 → 6.
  4. Add: 25 + 6 = 31. Remove complete weeks: 31 − 28 = 3.
  5. Add the century anchor: 4 + 3 = 7. The year anchor for 1981 is Saturday.
Why 28?

In this year calculation, 28 years contribute 28 + 7 = 35 days, exactly five weeks. Subtracting 28, 56 or 84 from the last two digits therefore preserves the remainder. Apply this shortcut within the year’s last two digits; the century anchor handles century changes.

For a year ending in 00, every year step is 0. The year anchor is simply the century anchor.

1Sunday2Monday3Tuesday4Wednesday5Thursday6Friday7Saturday

BDAY numbers the weekdays from Sunday = 1 to Saturday = 7. A remainder of 0 means Saturday when you turn a final weekday total into a day number.

Exercise

1994

Solved without revealing0

Weekday numbers: 1–7. Intermediate remainders: 0–6. No rounding up.

This session only. Each exercise counts once.

Next training stage →

Gregorian calendar, years 1–9999. Earlier dates are calculated using Gregorian rules extended backwards; historical local calendars may differ.