Question 1133835
10 to the -15 power/ 3.9 x 10 to the -7 power 
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1e-15/3.9e-7 = (1/3.9)e-8

=~ 0.25641e-8
=~ 2.5641e-9 or {{{2.5641*10^-9}}}
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{{{10^-15/(3.9*10^-7)}}}
Multiply NUM and DEN by 10^7
{{{10^-8/3.9}}}
= (1/3.9)*10^-8
=~ 0.25641*10^-8
=~ {{{2.5641*10^-9}}}