Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

Unique Properties of 80

  • The diagonals of a regular octagon divide it into 80 regions
  • 80 is the smallest cubeful integer with a cubeful successor
  • There are 80 four-digit primes which are concatenations of two-digit primes
  • 80 is the smallest number that is diminished by taking its sum of letters (writing out its English name and adding the letters using a=1, b=2, c=3, ...) - EIGHTY = 5+9+7+8+20+25 = 74
  • 80 is the smallest number n where n and n+1 are both products of 4 or more primes
  • 80 is the smallest number that appears in its factorial three times

Common Properties of 80