Revelation 17:9

This calls for a mind with wisdom. The seven heads are seven mountains on which the woman sits.

Revelation 13:18

This calls for wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man; its number is six hundred and sixty-six.

Revelation 17:3

And he carried me away in the Spirit into a wilderness, and I saw a woman sitting on a scarlet beast which was full of blasphemous names, and it had seven heads and ten horns.

Matthew 13:11

And he answered them, "To you it has been given to know the secrets of the kingdom of heaven, but to them it has not been given.

Matthew 24:15

"So when you see standing in the holy place 'the abomination of desolation,' spoken of by the prophet Daniel (let the reader understand)

Revelation 13:1

And the dragon stood on the shore of the sea. And I saw a beast coming out of the sea. He had ten horns and seven heads, with ten diadems on his horns, and on his heads were blasphemous names.

Revelation 17:7

And the angel said to me, "Why do you wonder? I will tell you the mystery of the woman and of the beast that carries her, which has the seven heads and the ten horns.

Revelation 17:18

The woman that you saw is the great city which has dominion over the kings of the earth."

Treasury of Scripture Knowledge

Summary

And here is the mind which hath wisdom. The seven heads are seven mountains, on which the woman sitteth.

Bible References

Here

Revelation 13:18
This calls for wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man; its number is six hundred and sixty-six.
Matthew 13:11
And he answered them, "To you it has been given to know the secrets of the kingdom of heaven, but to them it has not been given.
Matthew 24:15
"So when you see standing in the holy place 'the abomination of desolation,' spoken of by the prophet Daniel (let the reader understand)

The seven

Revelation 17:3
And he carried me away in the Spirit into a wilderness, and I saw a woman sitting on a scarlet beast which was full of blasphemous names, and it had seven heads and ten horns.
Revelation 13:1
And the dragon stood on the shore of the sea. And I saw a beast coming out of the sea. He had ten horns and seven heads, with ten diadems on his horns, and on his heads were blasphemous names.