50 (fifty) is the natural number following 49 and preceding 51.

Fifty is the smallest number that is the sum of two non-zero square numbers in two distinct ways.^[1] 50 is a Stirling number of the first kind and a Narayana number.

• The fifth magic number in nuclear physics

• The traditional number of years in a jubilee period.^[2]
• In Hindu tantric tradition, the number 50 holds significance as the 50 Rudras in the Malinīvijayottara correlate with the 50 phonemes of Sanskrit, as well as with the 50 severed heads worn around goddess Kali's head. The mantra Aham ("I am"), as laid out in the Vijñāna Bhairava represents the first अ(a) and last ह(ha) phonemes of the Sanskrit alphabet and is believed to represent ultimate reality, in accordance with its non-dual philosophy.

• The percentage (50%) equivalent to one half, so that the phrase "fifty-fifty" commonly expresses something divided equally in two; in business this is often denoted as being the ultimate in equal partnership
• In years of marriage, the gold or "golden" wedding anniversary