Question 148451
1.3 x 10(-12) is the diameter, and the radius is half of that.  So just multiply 1.3 x 10 by half of what you already did.  What I mean is this:


{{{1.3*10(-12)}}} becomes {{{1.3*10(-12/2)}}}


Simplify that and get {{{1.3*10(-6)}}}


{{{1.3*10(-6)}}} meters is the radius.