Isaiah 6:13 "And there will still be in it a tenth and it must again become something for burning down, like a big tree and like a massive tree in which, when there is a cutting down of them, there is a stump; a holy seed will be teh stump of it."
The one-tenth stump is the holy stump of natural Jews. The entire tree is thus ten times the size of the stump so the total number to be debated of combined Jews and gentiles is actually one million four hundred and fourty-four thousand (1,440,000).
But it seems that everyone that is "invited" doesn't truly fulfill the requirements. When Christ arrives, for instance many invited beg off and don't come resulting in many unfilled seats in the kingdom that are then filled with easterners and westerners, those not even Christians. So everyone has a chance, an "invite" to get into the kingdom, but many, many fail for one reason or another, so many that the 1,440,000 is not completed by Jews and Christians and so the full number is completed by whomever God chooses. Thus a huge failure rate should be factored in for all those considered as part of the 144,000. "Many are invited, but few chosen."
Even so, it would appear there is truly no problems with the numbers in this case, especially when the correct numbers are understood. 1,440,000 still isn't that large of a number comparatively, but admittedly easier to deal with than just 144,000.