You're correct, I apologize, I must have messed up somewhere in there.
I've got an average of 405 xp per battle, most of them doubled as I rarely play it more than 1-2 times a day, in order to get the doubled game, unless an event is going on due to the cost. That number is probably significantly lower than it will be for the rest of the grind, however, as I only recently unlocked the BL-9 gun which actually lets me start doing damage with the tank.
Let's assume I can average 1000 xp earned per battle, which isn't unreasonable and probably a little low if I only work daily doubles. It would take me somewhere around 318 battles to move up to tier 10.
I'm honestly not sure what happened to my math there, but it was wrong, so thanks for calling me out on it. I think that's one of the calculations I made the mistake of not double checking with a calculator, since it seemed simple enough, I also forgot to count in the experience needed to earn the Bl-9 gun which changed things a bit as well, but the main problem was my math skills.
I'm far from a great player, I'll be the first to admit, I'd even hesitate to call myself decent, but I am at least slightly above average judging from win% for whatever that is worth(not much, IMHO, but it's the only easy to see statistic I know anything about relative to the global rate)