Seven. It’s the lucky number. It’s a holy number. It’s the number you need to win several gambling games. It’s also Bungie’s favorite number, and the source of much annoyance in the Halo community when it comes to Halopedia’s list of references to the number.
"Some of you may be wondering - "What's up with this unhealthy obsession with the number 7?" This page offers some insights."
—Luke Smith, linking to Halopedia
The number seven appears in the Halo series quite often. It is Bungie’s calling card, like how Weird Al uses the number 27 in a ton of songs, or how Ahnold always says “I’ll be back.” People expect it and they actively seek out any references to the number seven. However, this search can be quite overzealous.
In their efforts to find anything that could be a seven reference, people often hit upon random connections that Bungie did not intend. The human brain is built to recognize patterns, and this can make it hard at times to determine whether there really is a pattern or if we’re just examining random data.
I decided to try and figure out how common seven references really are. I read through the book Halo: Ghosts of Onyx and made a note of each number and whether or not it related to seven. My data and results are accessible here. The short version is below:
There are a total of 921 unique numbers referred to in Ghosts of Onyx. 15 of them are unrelated scientific facts that should not be considered as part of the result. Discounting the 15 unrelated, there are then 906 total numbers. Out of these, there are 772 negative hits, which have no reference to the number seven. That makes 134 potential references.
The potential references are made up of four different categories: explicit (containing the number 7 itself), exponents, other multiples of 7, and multi-step addition (numbers that are broken down into digits and added up). There are 95 explicit hits, 2 exponents, 5 other multiples, and 32 multi-step numbers. I personally find everything but the explicit instances and the exponents to be tenuous at best, which would leave a total of 97 potential references out of 906 (or 921) total numbers.
As you can see, there are far more negative hits than there are even potential hits. Many of the potential references are sketchy, leaving only a few certain references, K7-49, for instance. That’s the explicit number and an exponent in one. Others, like the drug 88947-OP24, are probably just total coincidences. While shows like Lost may make every effort to fit each number into their mythology, this doesn’t seem to be the case with Bungie even with their love of 7. Maybe Ghosts of Onyx is just a bad choice for representing seven references, but given that it’s a pretty hefty Halo book, I believe it’s wise to consider that there aren’t as many seven references as people often think.