"Kvinnen har hundretalls katter i huset."

Translation: The woman has hundreds of cats in the house.

[duololz]

that escalated quickly

[Ambrose_Burnside]

well those thirteen black cats from the earlier lesson have been busy, now there's hundreds!

[hmada993]

Suddenly everything makes sense.

[yagsfan]

Apparently, they are not fixed. LOL

[Philosowater]

So, clarifying: would "hundrevis av" be acceptable/preferred here?

[Deliciae]

You can use either of the two, with "hundrevis av" being the more prevalent.