Counting the number of days between dates to exclude leap years

This was an interesting one. So what I did first was create a list of years (starting in 1920 – see cell E3 in the List of years sheet)

Then (with the help of Co-pilot) I created a formula that identified if a year was a leap year or not.  These are the rules for identifying if something is a leap year or not.  The mod() function was used to identify if a year was divisible by 400, 4 or 100.  I created a table of years which identified if something was a leap year or not.

Then I did a formula that pulled in the year of the starting date from the Leap year days calculations ( C5) and the year of the ending date (D5) . I then created a countifs()  function to count the number of  “Y” in the Leap year column which corresponded to the two years.

leap year calculation

You can see the video here.