4 ms·

To save some maths during a crisis - 3 is ~100m, 4 is ~10m.

• HPsquared 2y ago
  Lat/long coordinates and metres are actually linked quite closely: the metre was originally defined as "the arc from equator to North pole is defined as 10,000 km". That is, 90 degrees is 10,000 km.
  • jameshart 2y ago
    And if the French had had their way, we’d use grads not degrees and latitude would instead be 100 grads per 10,000km, so each grad of latitude would be 100km. That kind of sanity was, of course, unacceptable to the rest of the world.
    • HPsquared 2y ago
      The French were really into decimalization for a while. They tried decimal time (10 decimal hours per day, each 100 decimal minutes, each 100 decimal seconds), and a new calendar with equal 30-day months (the extra days at the end were national holidays, in September in the Gregorian calendar). Also 10-day 'décades' instead of weeks.