45 (number)

Template:Infobox number 45 (forty-five) is the natural number following 44 and preceding 46.

In mathematics

45 as the difference of two nonzero squares (in orange)

45 is an odd number and a Størmer number, as well as the 9th triangular number and 5th hexagonal number. 45 degrees is half of a right angle. It is also the smallest positive number that can be expressed as the difference of two nonzero squares in more than two ways: $7^2-2^2$, $9^2-6^2$ or $23^2-22^2$.

In culture

Issue 45 of The North Briton was thought to be seditious but its publisher, John Wilkes, was celebrated as a champion of liberty. The number 45 was used as a symbol of support for him. Banquets were held with a theme of 45 while many items were produced showing the number or featuring it in some way. For example, a wig was produced with 45 curls.

See also

• 54 – 45 reversed