'Number' in the Bible

Then I looked and heard the voice of many angels in a circle around the throne, as well as the living creatures and the elders. Their number was ten thousand times ten thousand -- thousands times thousands --

Each of them was given a long white robe and they were told to rest for a little longer, until the full number was reached of both their fellow servants and their brothers who were going to be killed just as they had been.

Now I heard the number of those who were marked with the seal, one hundred and forty-four thousand, sealed from all the tribes of the people of Israel:

The number of soldiers on horseback was two hundred million; I heard their number.

Thus no one was allowed to buy or sell things unless he bore the mark of the beast -- that is, his name or his number.

This calls for wisdom: Let the one who has insight calculate the beast's number, for it is man's number, and his number is 666.

Then I saw something like a sea of glass mixed with fire, and those who had conquered the beast and his image and the number of his name. They were standing by the sea of glass, holding harps given to them by God.