Peredhel coinage
Semi-triangular coins that link into a set: nine passing as ten, and worth less the moment you break them apart
Peredhel does not mint round coins. Its money is cut in an odd near-triangular shape, flattened along one edge so that the pieces link into one another and hold. Nine linked together are spent as ten. Break the set apart and you are holding nine coins that are worth nine; the tenth unit of value existed only while they were joined.
The inconvenience is the point. The coinage was cut this way to teach two things at once: that a set is worth more than the pieces it breaks into, and that money should be parted with deliberately rather than a coin at a time. The lesson is stamped into the money itself: stronger together.
Mikhail grew up spending it and explained it to nobody in particular on the road; the rest of the party worked it out for themselves later when a linked set came through their hands and the sum did not add up. The accounts differ on which coins were being linked that day (coppers passing for a silver, or silvers passing for a gold), and the rule holds either way.
Beyond the linking, the denominations are ordinary and are set out under currency.