What two number multiply to get negative 18

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters

Reinel saves 30% of every pay check. his paycheck last week was 560$. how much did reniel save last week?

What is the absolute value of -100000000000000?