What the day logo
What the Day
LearnPracticePlayDailyGuides
LearnGuidesPracticePlayDaily challengeLeaderboardAboutContactPrivacy
Copyright © 2026 Jesper Kiledal
All rights reserved
☕Buy me a coffee
What the day logo
What the Day
LearnPracticePlayDailyGuides

July 20, 1970 was a
Monday

July 20, 1970 was a Monday — that’s 20,411 days ago. Below you can see exactly how to work the weekday out in your head with the Doomsday algorithm, along with a few other facts about the date.

Weekday
Monday
Day of year
201 of 365
ISO week
Week 30
Leap year?
No
Zodiac sign
Cancer
Days ago
20,411

How to solve: July 20, 1970

  1. 1
    Century anchor1900s→Wednesday (3)
    Practice →
  2. 2
    Divide by 1270 ÷ 12→5
    Practice →
  3. 3
    Remainder of 1270 % 12→10
    Practice →
  4. 4
    Divide remainder by 410 ÷ 4→2
    Practice →
  5. 5
    Year's doomsday(3 + 5 + 10 + 2) % 7→6 → Saturday
    Practice →
  6. 6
    Month doomsdayJuly→11th
    Practice →
  7. 7
    Distance20 − 11→9
    Practice →
  8. 8
    Final answer(6 + 9) % 7→1 → Monday

On this day in history

  • 1969Apollo 11 Moon Landing

Related dates

Day beforeJuly 19, 1970 — SundayDay afterJuly 21, 1970 — TuesdayOne year earlierJuly 20, 1969 — SundayOne year laterJuly 20, 1971 — Tuesday
Want to be able to do this for any date in seconds? Read the guide or practice the algorithm.
Did you know? Did you know that Monday is the only day of the week when the U.S. stock market is more likely to decline than on any other day?