Underwood cast a baleful look at the coins, and grumbled evocatively. "…Math."
Bee-beep! Sparky peeked out of the reporter's jacket pocket. Underwood looked a bit thoughtful, tapping his chin once. "Huh. Now you mention it…"
He turned to the rest of the group: "Excuse us for a moment." There followed an adorable, several-minutes-long conference, with Underwood kneeling down by the coins next to Sparky to hash out ideas. On Underwood's part, this meant spirited discussion at a low mutter; on Sparky's, it meant a complicated player-piano-on-random MIDI sequence, ample dancing around, and what looked like Microsoft Excel.
"Okay." Underwood stood up, extending his hand for Sparky to clamber up and into -- the phone apparently wanted a good angle for presentation. "I'm going to let my partner do the talking on this, since it's his ballgame; if I get the translation wrong, that's on me."
The phone chittered away on his palm, flicking through charts, as Underwood summarized in short bursts. "He says a good way to think about it is number the coins from one to twelve. First weighing, we should do four coins against four coins: it doesn't matter which ones specifically, but, say -- not now, buddy -- 1 through 4 on the left against 5 through 8 on the right. If the left side is heavier, the odd coin's on that side and we're going to weigh coins 1 through 4 next; if the right side is heavier, we're going to weigh 5 through 8 next for the same reason. If both sides are the same, then the odd coin's one of 9 through 12, so we weigh those next -- not now."
"Whichever way it comes out, he says, we've got four coins we're weighing next, one of which is the heavy bit. So first weigh two of those versus the other two, pick the heavier side, and weigh one of those coins versus the other, to pick the heaviest. That's three weighs total -- now hold on just a second -- no matter which way you slice it."
He exhaled, glancing at Sparky, and addressing what the phone had apparently been bringing up at intervals the whole time. "Also…he says can he say hi to Miss Pleasant, because she looks nice."
This was possibly a charitable paraphrase of what Sparky had said, but the phone was clearly enthusiastic about it, jumping in Underwood's hand and beeping happily. The reporter looked at Cinder. "Miss Pleasant?"