55 (number)
Template:Infobox number 55 (fifty-five) is the natural number following 54 and preceding 56.
Mathematics
55 is:
- the 10th Fibonacci number<ref>{{#invoke:citation/CS1|citation
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- the 5th heptagonal number,<ref>{{#invoke:citation/CS1|citation
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55 is also the 19th semiprime and the 15th squarefree semiprime,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> as well as the 32nd nontotient number (including odd numbers > 1)<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> the 36th arithmetic number,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> the 38th composite number<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> (where the abundance of 55 = - 38),<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> the 43rd deficient number,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> the 45th trapezoidal number,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and the 49th polite number.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
In addition, the first 10 non-zero numbers added together equal 55. (1+2+3+4+5+6+7+8+9+10 = 55)
Transportation
- In the United States, the National Maximum Speed Law prohibited speed limits higher than Template:Convert 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".<ref name="HoldemSecrets">{{#invoke:citation/CS1|citation
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