### How many Sudoku puzzles are there?

There are a total of 6,670,903,752,021,072,936,960 possible solutions, yet when mathematicians took away rotations, reflections, permutations and relabeling, which takes away the same puzzle in just a different form, the number of solutions was 5,472,730,538.

Yelling “fore” is simply a shorter way to yell “watch out ahead” (or “watch out before”). It allows golfers to be forewarned, in other words. Any golfer who hits an errant shot that sends their golf ball hurtling toward golfers ahead should yell out “fore” as a warning.

According to Herodotus, the Lydians were the first people to introduce the use of gold and silver coins. It is thought by modern scholars that these first stamped coins were minted around 650–600 BC. The system of commodity money eventually evolved into a system of representative money.

ENIAC. ENIAC (/ˈini.æk/ or /ˈɛni.æk/; Electronic Numerical Integrator And Computer) was the first electronic general-purpose computer. It was Turing-complete, digital, and capable of being reprogrammed to solve “a large class of numerical problems”.

J. M. Barrie did not invent the name Wendy for his 1904 play Peter Pan, the Boy Who Wouldn’t Grow Up (the book form of the story, Peter and Wendy, was published in 1911). He did popularize it, though. Barrie apparently was inspired to use the name by a young friend named Margaret Henley, the daughter of writer William Henley. Margaret, who died around 1895 at age 6, called Barrie her “friendy.” Since she couldn’t pronounce her Rs at the time, the word came out “fwendy,” or “fwendy-wendy,” in some versions of the story. But we have absolute proof that there were earlier Wendys, thanks to the just-released 1880 U.S. Census and the 1881 British Census. These documents show that the name Wendy, while not common, was indeed used in both the U.S. and Great Britain throughout the 1800s.

Migraines are disabling headaches that most likely stem from problems with the nerves and blood vessels in the head. Migraine headaches typically last from 4-72 hours. They may occur as often as several times a week to only once a year. People who have migraines are called migraineurs.

Jonas Salk. Jonas Edward Salk (October 28, 1914 – June 23, 1995) was an American medical researcher and virologist. He discovered and developed the first successful inactivated polio vaccine.

The only remaining nonmetric countries in the world are the United States, Liberia, and Myanmar (Burma). Our conversion calculator can help convert between the metric system and U.S. Weights and Measures.