50

50 is the natural number that comes after 49 and before 51. In decimal notation it is written as 50. In Roman numerals it is L. The word fifty comes from Old English fīftig, built as a combination of five and a tens-indicating suffix, effectively meaning “five tens.”

Mathematically, 50 is a composite number with prime factorization 2 × 5^2. It has six positive divisors: 1, 2, 5, 10, 25, and 50. The sum of its proper divisors is 43, so 50 is a deficient number. In various numeral systems, 50 is represented as 110010 in binary, 062 in octal, and 0x32 in hexadecimal.

In science, element 50 is tin (Sn). Tin is a malleable post-transition metal used in solder, tin plating, and various alloys.

Culturally, fifty is often viewed as a milestone or “round number.” A 50th anniversary is traditionally associated with gold. The United States uses fifty stars on its flag to represent the states, and Hawaii is the 50th state, admitted in 1959. The year 50 is also associated with the Jewish Jubilee tradition, which is said to occur every fifty years. In sports, the 50-yard line marks midfield on many football fields.

Geometrically, a polygon with 50 sides is called a pentacontagon. The number appears in various practical and symbolic contexts as a round, milestone figure.