deletions | additions       diff --git a/Box.tex b/Box.tex  index fb41589..a549a69 100644  --- a/Box.tex  +++ b/Box.tex 
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$N =\overbrace{R}^{\sim10} \times \overbrace{f_p}^{\sim 1} \times \overbrace{n_e}^{\sim 0.2} \times \underbrace{f_l \times f_i \times f_c \times L}_{?}$ So the product of the first 3 terms, now well estblished, is of order 1. So we can simplify the Drake equation and re-write it as   $N \approx \underbrace{f_l \times f_i \times f_c \times L}_{?}$