55 (fifty-five) is the natural number following 54 and preceding 56.
Mathematics
thumb|55 is a square pyramidal number.
55 is composite number, a Fibonacci number and a Triangular number.
Transportation
- In the United States, the National Maximum Speed Law prohibited speed limits higher than from 1974 to 1987. The number 55 became a popular shorthand for the 55 mph speed limit. For example, a hand with a pair of fives in Texas hold'em poker is referred to as a "speed limit".