An A330 Flight Crew received inaccurate weight and balance information for takeoff calculations.

Narrative

In receiving our weight and balance; it was for the arrival Runway 9R. When we requested the departure runway; we received weight and balance numbers we intuitively knew were wrong; but could not immediately find the mistake. We asked to have the numbers run again and got the same result. Since we could not find the error; and we knew something was wrong; we chose to depart on Runway 9R for which the weight and balance matched our experiences with weight and balance. Later without time pressure; the error was found to be in the MTOW [Maximum Take-off Weight]. The wrong number was used.I am not sure why the MTOW was imputed incorrectly by load control. Since it is a number that does not change we in the cockpit were not looking for that kind of error.It is unknown how the MTOW was a variable in load planning. There was a Captain acting as an relief pilot. I am sure a regularly assigned relief pilot; whose duties are to regularly evaluate the weight and balance; would have found this error much more quickly.