[She watches his hands move, head tilted to the side. When he forms the 10 it takes her a second before she lets out an "oh!"] Your name is Ten? That's... hm. [She considers, pausing her hammering to pat some dirt off of her leggings.]

We've fought three... of you... so far. I don't suppose your name means you'll be number ten? [She doesn't call him and his friends "monsters", just in case. Maybe they don't know they're monsters, and she'd seem super rude! How would she know? Spoilers: she's probably going to ask.]