Societies often treat numbers with care, even reverence. They may be mystical, magical, symbolic or simply a mnemonic tool. During World War II, the combination of the safe in the German Embassy in Turkey was Hitler's birthday. Many years ago, the combination code of the door to a USAID mission in Asia was 1776, the year of the Declaration of Independence. In the West, perhaps the best-known number of significance is 13, a supposed harbinger of bad luck based, some say, on the number of people at Christ's Last Supper.