Last week, as part of Wired's nine-week-long geek-list parade, we gave you nine equations that we think every true geek should know (or at least pretend to know). This week, we bring you some of the equations our readers think should have been on that list.

Which list is the geekiest? We'll leave that up to you.

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Fifty years ago astronomer Frank Drake attempted to estimate the number of detectable alien civilizations in our galaxy. The result is this well-known equation, which many readers felt had been overlooked.

Drake’s equation states that the number of extraterrestrial civilizations in the Milky Way could be estimated by knowing several key factors, including the rate of star formation, the number of stars with planets, the number of planets that can host life and the fraction of life-bearing planets that evolve intelligent beings on them. Since it was written, astronomers have refined several of the terms, such as the number of nearby exoplanets, but many of the values in this formula are yet to be determined.

Commenter Brent pointed out that the Drake equation is “relatively new and represent[s] still-expanding fields of knowledge” while Bill Parrott added that “the concept of life throughout the universe is one that geeks of any ilk can all get excited about.”

Image: The Arecibo Observatory in Puerto Rico, which has been used to both to search for alien radio signals and transmit our own message from Earth into space. H. Schweiker/WIYN and NOAO/AURA/NSF