“Where did you learn that trick?” he asked. “I thought those things could only add and subtract.”

“Well—multiplication’s only repeated addition, isn’t it? All I did was to add 856 seven times in the unit column, three times in the tens column, and four times in the hundreds column. You do the same thing when you use pencil and paper. Of course, there are some short cuts, but if you think I’m fast, you should have seen my granduncle. He used to work in a Yokohama bank, and you couldn’t see his fingers when he was going at speed. He taught me some of the tricks, but I’ve forgotten most of them in the last twenty years. I’ve only been practising for a couple of days, so I’m still pretty slow. All the same, I hope I’ve convinced you that there’s something in my argument.”

“You certainly have: I’m quite impressed. Can you divide just as quickly?”

“Very nearly, when you’ve had enough experience.”

Martens picked up the abacus, and started flicking the beads back and forth. Then he sighed.

“Ingenious—but it doesn’t really help us. Even if it’s ten times as fast as a man with pencil and paper—which it isn’t—the computer was a million times faster.”

“I’ve thought of that,” answered Pickett, a little impatiently.

(Martens had no guts—he gave up too easily. How did he think astronomers managed a hundred years ago, before there were any computers?)

“This is what I propose—tell me if you can see any flaws in it…”

Carefully and earnestly he detailed his plan. As he did so, Martens slowly relaxed, and presently he gave the first laugh that Pickett had heard aboard Challenger for days.

“I want to see the skipper’s face,” said the astronomer, “when you tell him that we’re all going back to the nursery to start playing with beads.”

There was scepticism at first, but it vanished swiftly when Pickett gave a few demonstrations. To men who had grown up in a world of electronics, the fact that a simple structure of wire and beads could perform such apparent miracles was a revelation. It was also a challenge, and because their lives depended upon it, they responded eagerly.