Scoring in football tends to take place an average of only about 8 times a game and as a result of few scores; the final scores do group around certain numbers, known as key numbers. The major key numbers are 3 and 7, but 1, 4, 6, 10, 13 and 14 have a high likelihood of being the final margin of victory as well and are sometimes referred to as minor key numbers. If we look at how all these numbers relate to 3 and 7, its easy to see why they occur frequently. The following chart shows the frequency of certain final scores for the 2002 NFL season as well as the relationship of the number to a combination of Touchdowns and Field Goals:
3 16.0% Field Goal
7 11.3% Touchdown
6 6.6% 2 Field Goals
10 5.1% Touchdown + Field Goal