Every Hebrew letter has a numerical value. An Aleph, the first letter, has a value of one. The second letter, Bet, has a value of two. . As a result, words can be expressed numerically...the word for 'life' in Hebrew is "Chai" (as in 'l'chaim' - 'to life'). It is spelled with two Hebrew letters, the 'chet', which has a value of 8 and 'yud' which has a value of 10. Added together, the word 'chai' has a value of 18