Thanks for the replies AOW and Coyote.
Its been a while since I did those Aussie ATPL's.... negative experiences tend to be forgotten over time .......
I think I may have confused the issue. What I more accurately needed was a calculation of the actual fuel burnt considering DA etc.
eg: indicating a burn of 600lb but due to being at 20000' (dodging 737's in the 76) the actual burn is maybe 500lb's
Thanks for your time in reply...