find the height of a cylinder with a volume of 100cm^3 and a radius of 2 cm

The volume of a cylinder is given by pi*r^2*h where r is the radius and h is the height.  So pi*2^2*h = 100

therefore h = 100/(pi*4) cm or

  $${\mathtt{h}} = {\frac{{\mathtt{100}}}{\left({\mathtt{\pi}}{\mathtt{\,\times\,}}{\mathtt{4}}\right)}} = {\mathtt{h}} = {\mathtt{7.957\: \!747\: \!154\: \!594\: \!766\: \!8}}$$

you do pi 3 to the 4 times pi to the 8^201  then divide by 3000