hi...
i am trying to create a database for a company, now the problem i am
facing is this.... i want to write a formula which would sum up certain
cells but that data is in another worksheet. so i wanna combine the
sum function and the vlookup function i guess .. but i cannot
understand how. Consider this ..

Machine hours Tonnage

12 90
20 120
5 120
7 210
25 320

Both these columns are in one worksheet say 'data' I want to
display the sum of the m/c hrs corresponding to the tonnage (for 120 it
is 25) in another worksheet say 'machine hrs'. how can I do that ?
Also if any of you ppl can tell me how to use vlookup for combining
two worksheets.. it would be a great help if anyone can shed some
llight on this... thanx in advance ...

adi