she does math in her sleep

I stayed up later than Greg and the kids tonight to make cupcakes for Stephanie's class tomorrow. The kids were snuggling with Greg in our bed and they all fell asleep. A couple of times I heard someone talking well after I knew they'd gone to sleep. I wondered which of the girls was talking in her sleep.

I got hooked on my book, as usual, and just now went in there to coax them to their beds. When I tried to wake Heather enough to walk she opened her eyes and fixed her glassy stare past me. Then she whispered, "Zero."

I'm guessing she was the sleep-talker. I'm also guessing she's doing some math right about now.