Abacus
A calculating tool that stores the digits but leaves the algorithm to the human — which is why it can still beat a trained machine operator.
Counting frames descend from the counting boards of Mesopotamia, where loose pebbles — Latin calculi — were shifted between columns. The Chinese suanpan, the Japanese soroban and the Russian schoty are one idea in three executions: beads on rods, each rod a place in the number system.
The interesting part is the division of labour. The abacus holds the intermediate result, which is its entire job, while the arithmetic itself lives in the operator's fingers and head. A fluent soroban user writes nothing down, and when Stars and Stripes staged a contest in Tokyo in 1946 between Kiyoshi Matsuzaki and a US Army operator on an electric calculator, the abacus took four of the five events. It lost on multiplication of large numbers.
It survives in Japanese schools and among blind calculators, in both cases for the same reason: it builds a feel for magnitude that a display never gives.