1) The sum of the first 31 odd prime numbers is a perfect square:
3 + 5 + 7 + 11 + ... + 83 + 87 + 89 = 31 x 31
2) There are 31 letters in the Cyrillic (Russian) alphabet.
3) Thirty-one is a betting game played with cards.
4) In French the expression trente et un (31) refers to someone who is well dressed.
5) There are 31 days in most months.
6) a billion seconds is (roughly) 31 years...
and
7) WHQR is 31 years old today!
THANKS TO OUR LISTENERS FOR MAKING LOCAL PUBLIC RADIO A REALITY FOR ONE BILLION SECONDS!
AND COUNTING!
sources:
http://www.archimedes-lab.org/numbers/Num24_69.html
http://www.richardphillips.org.uk/number/Num31.htm