Revelation concerns a great City[Jerusalem] and Country[Israel,Judea]
not the world.
Jerusalem and the Temple was the center of the world for the Jewish nation.
There is no estimate I could find concerning the number of Jews living in and around Israel and Jerusalem/Judea in the 1st century leading up to the 70ad destruction of Jerusalem [then the last Jewish stronghold of Masada in 73ad.]
Josephus estimates around a million Jews perished in 70ad and that was mainly because Jews from all over came to celebrate Passover:
The Destruction of Jerusalem - George Peter Holford, 1805AD
The day on which Titus encompassed Jerusalem,
was the feast of the Passover ; and it is deserving of the very particular attention of the reader, that this was the anniversary of that memorable period in which the Jews crucified their Messiah ! At this season multitudes came up from all the surrounding country, and from distant parts, to keep the festival. How suitable and how kind, then, was the prophetic admonition of our LORD, and how clearly he into futurity when he said "Let not them that are in the countries enter into Jerusalem." Luke xxi. 21.
Nevertheless, the city was at this time crowded with Jewish strangers, and foreigners from all parts, so that the whole nation may be considered as having been shut up in one prison, preparatory to the execution of the Divine vengeance ; and, according to Josephus this event took place
suddenly ; thus, not only fulfilling the predictions of our LORD, that these calamities should come, like the swift-darting lightning" that cometh out of the east and shineth even unto the West," and " as a
snare on all of them (the Jews) who dwelt upon the face of the whole earth " (Matt. xxiv. 27, and Luke xxi 35,) but justifying, also, his friendly direction, that those who fled from the place should use the utmost possible expedition.
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His estimate of the number of Jews slaughtered thru sword, famine and fire:
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Of the Jews destroyed during the siege, Josephus reckons
not less than ONE MILLION AND ONE HUNDRED THOUSAND,
to which
must be added, above
TWO-HUNDRED AND THIRTY-SEVEN THOUSAND who perished in other places,
and
innumerable multitudes who were swept away by famine, and pestilence, and of which no calculation could be made.
Not less than
two thousand laid violent hands upon themselves. Of the captives the whole was about NINETY-SEVEN THOUSAND. Of the Two great leaders of the Jews, who had both been made prisoners, John was doomed to a dungeon for life ; while Simon, together with John, in triumph at Rome was scourged, and put to death as a malefactor.
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Eze 5:
2 “You shall burn with fire
one-third in the midst of the city, when the days of the siege are finished; then you shall take one-third and strike around
it with the sword, and one-third you shall scatter in the wind: I will draw out a sword after them.
12 ‘One-third of you shall die of the
pestilence, and be consumed with
famine in your midst; and one-third shall fall by the
sword all around you; and I will scatter another third to all the winds, and I will draw out a sword after them.
Mat 24:7
Nation will rise against nation, and kingdom against kingdom. There will be famines and earthquakes in various places.
Mar 13:8
Nation will rise against nation, and kingdom against kingdom. There will be earthquakes in various places, and famines. These are the beginning of birth pains.
Luk 21:11
There will be great earthquakes,
famines and
pestilences in various places, and fearful events and great signs from heaven.
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Rev 16:2
The first angel went and poured out his bowl on the land, and
ugly, festering sores broke out on the people who had the mark of the beast and worshiped its image.
Rev 16:11
and cursed the God of heaven because of their pains and their
sores, but they refused to repent of what they had done.
Rev 9:15
And the four angels who had been kept ready for this very hour and day and month and year were released to kill
a third of mankind.
Rev 9:18
A third of mankind was killed by the three plagues of fire, smoke and sulfur that came out of their mouths.
Revelation 18:
15The merchants of these things, who were made rich by her,
will stand far away for the fear of her torment, weeping and mourning;
16saying, 'Woe, woe,
the great city, she who was dressed in fine linen, purple, and scarlet, and decked with gold and precious stones and pearls!
17For in an hour such great riches are made desolate.' Every shipmaster, and everyone who sails anywhere, and mariners, and as many as gain their living by sea, stood far away,
18and
cried out as they looked at the smoke of her burning, saying, 'What is like the great city?'
19They cast dust on their heads, and cried, weeping and mourning, saying, 'Woe, woe, the great city, in which all who had their ships in the sea were made rich by reason of her great wealth!' For in one hour is she made desolate.