12. Decimal Addition

Evening settled over Dorpat like ink across parchment—slow, inevitable, and absolute. The last rays of sun spilled across the snow-dusted rooftops, then vanished, leaving only lamp-glow and silence in the long corridors of the mathematics wing.

Mihkel stood outside the archive room, hand on the door’s iron handle. He had not been summoned—Professor Reichenstein did not summon—but a note had arrived nonetheless: „If you care for generality as much as you seem to, meet me at dusk. No theatrics. Bring a mind fit for method.“

Inside, Reichenstein sat alone beneath a sputtering gas lamp, surrounded by ledgers, inkpots, and the sharp odor of melted sealing wax. He did not look up as Mihkel entered.

„Sit,“ he said, sliding a sheet across the table. On it, two columns of numbers—crates sold, coins collected, years tabulated in quiet ink.

„Addition,“ Reichenstein muttered, as if it were a slur. „Simple. But not to be treated simply. It is not enough to add two numbers—you must add any two. Build me a method, not a trick. One that works for 2 + 5, and 37 + 89, and 999 + 1, and many others. That is the task.“

Mihkel gave a small nod, betraying neither excitement nor dread. He folded the sheet, tucked it beneath his coat, and left with only a murmur of farewell.

Back in his quarters, he laid out the tape slowly. The digits gleamed dully in lamplight. “This is not the same as increment,” he thought. “It is everything increment tries to be—twice.”

Two numbers, two moving parts, a possible carry from each column to the next. The Mill had not yet faced this. It had known how to count—but now it must combine.

He worked through the night, not with fever but with clarity. This was no longer about solving a puzzle. It was about creating a mechanism of thought. A procedure that would not care what numbers it met—only how they were formed.

By morning, the Mill was quiet. And the tape was no longer two numbers. It was one answer.