Revelation 17:9

the meaning is very comprehensive. The seven heads are seven mountains, on which the woman sitteth.

Revelation 13:18

here is wisdom. let him that hath understanding count the number of the beast: for it is the number of a man; and his number is six hundred sixty six.

Revelation 17:3

so he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet-coloured beast, full of names of blasphemy, having seven heads, and ten horns.

Matthew 13:11

to whom he answered, because you are allowed to know the mysteries of the gospel-dispensation, but to them it is not allowed.

Matthew 24:15

When ye therefore shall see the abomination of desolation, mention'd by Daniel the prophet, stand about the holy place, (let him that readeth,

Revelation 13:1

Then I saw a beast rise up out of the sea, having seven heads, and ten horns; upon his horns were ten crowns, and upon his heads the name of blasphemy.

Revelation 17:7

and the angel said to me, wherefore didst thou marvel? I will tell thee the mystical meaning of the woman, and of the beast that carrieth her, which hath the seven heads and ten horns.

Revelation 17:18

and the woman which you saw, is that great city, which reigns the empress of 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
here is wisdom. let him that hath understanding count the number of the beast: for it is the number of a man; and his number is six hundred sixty six.
Matthew 13:11
to whom he answered, because you are allowed to know the mysteries of the gospel-dispensation, but to them it is not allowed.
Matthew 24:15
When ye therefore shall see the abomination of desolation, mention'd by Daniel the prophet, stand about the holy place, (let him that readeth,

The seven

Revelation 17:3
so he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet-coloured beast, full of names of blasphemy, having seven heads, and ten horns.
Revelation 13:1
Then I saw a beast rise up out of the sea, having seven heads, and ten horns; upon his horns were ten crowns, and upon his heads the name of blasphemy.