The word επτα (hepta) is the cardinal number seven, but it needs to be remembered that the ancients did not live in an arithmetically accurate world such as ours. Most Greek numbers were actually words (such as our word επτα, hepta, meaning seven) and only rarely the Greeks wrote their numbers using single Greek letters to represent single numerical digits — see for instance the famous number 666 in Revelation 13:18, which is spelled χξς (ch-x-s). But in each case, all Greek numbers looked like words and were mostly treated like words: fuzzy and subject to poetic license. This in turn meant that daily calculus was more of an art than science — the reason why young Asian children are usually better at calculus than their Western colleagues is that Asian languages represent numbers more consistently and more conductive of calculus than Western languages. When children learn to think in numbers, the advantage shrinks. And when Europeans adopted Arabic numerals, the Renaissance commenced.

Unless the context was clearly arithmetical (like: you owe me 2 bits for 4 apples), in Greek texts numbers came with a symbolic value that was similar to that of regular words, and were likewise subject to experience. An army of "ten-thousand men" may have actually consisted of 6754 enlisted troops but nobody cared about the number 6754 and only about the colossal threat this army posed. In our modern world, large round numbers still have the symbolic meaning of "a whole lot", but in the Greek world, smaller numbers too had meaning beyond their arithmetic nature. This has led many an aspiring prophet down the garden path of numerology, only to find that this garden path is rather steep, short and decidedly inanimate of termination. That's not to say that there's nothing there; it's just to indicate that even the meaning with which numbers are charged require a controlled, contained and inspired approach.

The Hebrew word for seven is שבעה (shib'a), which stems from a verb that means both "to be seven" and "to make an oath" (hence the name Elizabeth). It's also spelled identical to a verb that means to saturate (people with food or the earth with rain). Seven is the number of days in which God creates reality — because, no, the creation week is not the first week long ago but the grand super-structure of all evolution across all the ages; whatever evolves naturally, naturally evolves via seven stages (see for more our study of Genesis 1) — and by using the number seven, a Biblical author appears to mostly want to refer to the entirety of any natural cycle of growth or evolution that stands on any previous natural cycle of growth or evolution — hence the seven daughters of Jethro of Midian (Exodus 2:16); the seven pillar of wisdom (Proverbs 9:1); the seven deacons of the church (Acts 6:3; themselves an obvious nod to the proverbial Seven Sages of Greek tradition); the seven churches of Asia Minor (Revelation 1:4); and so on.

Our word επτα (hepta) meaning seven occurs a whopping 89 times in the New Testament, see full concordance, and from it come: