vidiot,
The ancient Hebrews were into the spiritual meanings of numbers. For example, each of the 22 letters of the Hebrew alphabet was assigned a numerical value. This meant that each word was also a number, by adding the value of each letter. It did not matter which order the letters were in. The term to look up on the www is gematria.
In addition, spiritual meanings were ascribed to each letter of the alphabet. Look up Kabbalah to get an idea of mystical Judaism.
This is important when reading the Bible. It is a collection of ancient Jewish documents and they need to be read in the context of each community that produced it and edited it. It is overlaid with these spiritual overtones. It is religious history, not a literal record.
Reading it through modern eyes fails to recognise the intention of a document. When they wrote 7 or 12 or 70, they did not have a calculator or a computer in mind, not even an abacus. Rather, they were using numbers to provide meaning (compare: 12 tribes, 12 disciples, 12 gates.)
Doug