24 (number)

24 was a number.

There were twenty-four hours in an Earth day. (TV: The Moonbase, Last of the Time Lords)

A night on Darillium lasted twenty-four years. (TV: The Husbands of River Song)

When the Twelfth Doctor asked Clara Oswald to pick a two-digit number, she chose 24. He then asked the crew of the crew to look at the first word of page 24 of the book they were holding, as part of the Helman-Ziegler test. (TV: Last Christmas)