Trowa is the best brother for mental math.

:D, her face says. "Ha! Okay, so single flip, you catch over here," she points to where he usually lands after a flip, "I'll have walked to here," she bops to where that is and taps the highwire above her head. "And flip--there--without hitting you in the head."

Thoughtful pause. "That shouldn't be hard, I'll just keep my right arm held in, which'll throw off my balance a bit but I can probably correspond it with my left."