Cycles and Time: Calendars

Methods in this video

Tap a time to jump to where the video teaches that method.

1. 1

   Skip whole weeks

   ▶ 1:21

   When to use it: The question tells you the weekday of one day and asks what weekday it is a number of days earlier or later (or on another date), and the gap is too long to count day by day.

   • A week is a 7-day cycle: move forward or back by whole weeks (7, 14, 21 days) and the weekday stays the same.
   • Skip the whole weeks and move only by the days left over; never drop those extra days (20 days is not 3 weeks, it is 1 day short).
   • If only the weekday is asked, find the exact gap in days, divide by 7 and use the remainder.
2. 2

   Jump to the month end first

   ▶ 2:49

   When to use it: The question moves a number of days forward or back from a date and asks for the new date, or asks how many days lie between two dates in different months (often followed by the weekday).

   • Going back, take off the date first to land on the last day of the previous month; going forward, first reach the last day of this month.
   • To count days across months, count the days left in this month, then add the date in the next month.
   • Know each month's length: knuckles are 31 days, dips are 30, July and August both have 31, and February has 28 or 29.