We get to this number by comparing the number of animals we take in to the number we adopt out. (indyhumane.org)
The team then compared those numbers with the number of operations actually performed with minimally invasive surgery. (sciencedaily.com)
We then compare the number of observed planet candidates to the number of stars around which such planets could have been detected in order to estimate the planet occurrence rate around cool stars. (arxiv.org)