Kind of a useless question, of course. In the old days the answer might indicate how adept one was with research. Now it just shows the bandwidth of your smart phone. It’s not hard to hop on the net and find the answer (tne Napoleon-Series is particularly useful): 89
John Elting states 90 for unaccounted reasons. The most likely explanation is that he is tipping his hat to the (coincidently) 89e régiment d’infanterie de ligne which had been struck off the rolls in 1803, but part of which continued to disintegrate in Haiti.