This is how I know, because I finally slide a textbook over my answer sheet, and he sort of smiles at me, like, gotcha. I mean, like you do when you’ve been playing a trick on somebody and they finally realize it. And when you don’t react, or at least, not the way they want you to, it’s like you’re the weird one because you don’t think it’s funny.

The last question of the day is a bonus question: 99 x 91.

“Anybody know this one?” Ms. Kaminski asks.

I like her, but she isn’t the kind of teacher who understands the kids very well. She always seems to be nice to the wrong ones. “All right, Pete,” she says at last, when nobody answers. “Go ahead.”

“I think we should let somebody else have a chance,” Pete tells her.

I put my hand up, and Ms. Kaminski finally notices me.

“Yes, Ben?” she says.

“Nine thousand and nine.”

“That’s right,” she says. “I’m impressed. Where’d you learn how to do that?”

“There’s a trick,” I tell her. “My dad showed me.”

Ms. Kaminski is standing in front of her desk, with her hands behind her back. She has a way of standing with her feet together, like a ballerina, totally still. And she uses her voice like she’s acting in a play—she says everything very clearly, like it was written down somewhere, and she’s trying to project her voice to the back of the room.

“Do you want to explain it to the rest of the class?”

My face feels hot; it’s all gone quiet, and when I start to talk, a couple of kids call out, “We can’t hear you.”

“Why don’t you stand up?” Ms. Kaminski says.

I push my desk back a little, but everybody’s looking at me. “You just . . . it’s when . . . it’s when you’re multiplying two numbers, and they end in . . . When the units add up to . . .” It sounds really . . . it sounds embarrassing, like, if you ask me what I’m really thinking, what I’m thinking about is tens digits and units digits, and I know what they’re all thinking. They’re thinking, What a nerd. Finally the bell rings. Ms. Kaminski tries to make them wait until I’ve finished, but everybody gets up anyway. It’s a relief.

Afterward, she stops me on the way out—she puts a hand on my shoulder and closes the classroom door. “I’m sorry I put you on the spot like that,” she says quietly. “You did great. Your dad must be a good teacher.”

She looks at me, and I don’t say anything. Her face is kind, but I don’t want to look back at her. “There’s nothing to be ashamed of,” she says. “There’s nothing wrong with liking math. Go on, get some lunch. You’ve earned it.”

Pete is waiting for me in the hallway.

“What’d you do that for?” he says. When Mabley isn’t around, he sounds totally different. His face has gone red, except for the tip of his nose, which looks pinched and white.