I need to input Diameter, Length, and pcs to calculate the total volumes of logs (logs calculator), the table is same like this 

dia,      len,      pcs,      vol,

15,       2.6,       5,       3.14*(15/200)^2*2.6*5

20,       2.6,       7,       3.14*(20/200)^2*2.6*7

then calculate the total volume.

How to design form in multiple columns?