Hi,
Yes, you can use a formula and use that where you want to display your D column data. Formula content is something like below:
if recordNumber = 1 then 0
else previous(<Database column representing column C>) - <Database column representing column C>
in case you don't want to display 0 for the first record under Column D, you can use a suppress condition at field level like below
if recordNumber = 1 then true
Hope this helps
Thanks,
Raghavendra