'Number' in the Bible

Each of them was given a white robe. They were told to rest a little longer until the number of their fellow servants and their brothers was completed, who would be killed as they themselves had been.

I heard the number of those who were sealed: 144,000. Those who were sealed were from every tribe of Israel:

The number of cavalry troops was 200,000,000. I heard how many there were.

so that no one may buy or sell unless he has the mark, which is the beast's name or the number of its name.

Then I saw what looked like a sea of glass mixed with fire. Those who had conquered the beast, its image, and the number of its name were standing on the sea of glass holding God's harps in their hands.