If you use a number format like 0, Excel simply writes the number with no decimal point or decimal digits. To truncate the last three digits of a number in the thousands, append a comma to the number format, like this: 0,. Two commas drop off two sets of three digits, etc. To add a character after the number, K for thousands, append it in quotes: 0,”K”. Here are a few sample formats for a number in the thousands:

Here is a conditional number format that shows numbers as millions with an M, thousands with a K, or as numbers:  [>=1000000]0,,”M”;[>=1000]0,”K”;0

Here is how some numbers appear in this format: