Question 893677
Your description is not too precise.  You seem to be saying, diameter accross the circular cross section is 36 inches, and distance from top circular surface to the bottom circular surface is 1 inch.


{{{h=1}}}
{{{d=36}}}
{{{r=d/2}}}
formula for volume:  {{{highlight_green(h*pi*r^2)}}}


To use what seem to be your values, 
volume is  {{{1*pi*(36/2)^2}}},
{{{pi*(18)^2}}}
{{{highlight(324*pi)}}}  cubic inches.


Multiplication by 1 should not cause confusion; just be sure you are keeping within the same measurement unit or properly converting whenever needed.  Your example seems to be all in inches.