45 (number)

← 44 45 46 →
← 40 41 42 43 44 45 46 47 48 49 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	forty-five
Ordinal	45th (forty-fifth)
Factorization	32 × 5
Divisors	1, 3, 5, 9, 15, 45
Greek numeral	ΜΕ´
Roman numeral	XLV, xlv
Binary	1011012
Ternary	12003
Senary	1136
Octal	558
Duodecimal	3912
Hexadecimal	2D16

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. 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