When expressing long lengths or distances in feet, we use a comma between the digits representing the hundreds and thousands. Example: 1,106 ft (Note that the units are ft and not feet.) However, when expressing long lengths or distances in meters, we do not use commas. Example: 1106 m (Note that the units are m and not meters or metres.) Why, you ask? Because in Europe and other metric-friendly places, commas and periods are used the opposite of how we use them in the USA, with commas as decimal points and periods as delimiters of three orders of magnitude. Non-US people would be terribly confused, and we don’t want that. So how shall we remember this rule? We can think of a comma as a little toe, and remember that feet have toes and meters don’t.