Contradiction or not?

When you multiply something by a hundred, you get more or bigger, right? In math class we used to add two zeros to a number to multiply it by a hundred. Well, take a look at this sentence:

The galaxies – 100 times less massive than our Milky Way – are now among the smallest known to host such big black holes.

Can you have something a hundred times less? If you can, what are you multiplying by a hundred?

Yes, the sentence is idiomatic, but still, I think it’s better to write what you mean. The sentence means one hundredth as massive.


Oh—here’s a picture:

Galaxy with inset illustration of a green spiral with jets coming out top and bottom.
Artist’s concept of a dwarf galaxy, its shape distorted, most likely by a past interaction with another galaxy, and a massive black hole in its outskirts (bright spot, far right). Image via Sophia Dagnello/ NRAO/ AUI/ NSF.