Main Page | See live article | Alphabetical index For the year A.D. 55, see 55. Fifty-five (55, LV) is the natural number following fifty-four and preceeding fifty-six. It is a triangular number, made up of the numbers 1 to 10 added up, and it is also the sum of the squares of the integers 1 to 5. It is also a Fibonacci number. Its divisors are 1, 5, 11, and 55; its factorisation is Fifty-five is also: The atomic number of cesium. The number of delegates who attended the Constitutional Convention. In gallons, a common size of drum containing liquids. In miles per hour in many states of the United States, a common speed limit; it was the national speed limit for a time during the Energy Crisis of the late 1970s. In years of marriage, the emerald wedding anniversary. The code for international direct dial phone calls to Brazil. The designation of United States Interstate 55, a freeway that runs from Louisiana to Illinois. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.