The number 18 stands for life. But to figure that out, you need to understand pre-modern number systems. Back before we had what we now call Arabic numerals (base 10 and the numerals 0123456789), different cultures tended to use letters for numbering. The system of Roman numerals is generally familiar, I II III IV V VI VII VIII IX, etc, but there were also number systems connected to the Greek and Hebrew alphabets. The Hebrew number system is called Gematria, and is still used for things like dates on Jewish tombstones. One feature that distinguishes Hebrew numerals from Roman is that the entire Hebrew alphabet is used. As a result, there is a numerical value associated with every Hebrew word. Life, pronounced Chai (the ch is hard, as in Bach or Loch Ness) is spelled Chet Yud, where Chet =