deletions | additions       diff --git a/Box.tex b/Box.tex  index dc0b7b6..6334c22 100644  --- a/Box.tex  +++ b/Box.tex 
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So the product of the first 3 terms is now well established and is, using a conservtive approximation, of order 1. So we can simplify the Drake equation and re-write it as:  $N \approx \underbrace{f_l f_l  \times f_i \times f_c \times L}_{?}$ L$