Information zur MC 24 Serie:
Andrea Celli: "The MC-24 series (Divisumma basic/GT/CR and Tetractys) was the most popular and
successful Olivetti machine. Circa 1.500.000 machines sold (In
internet you can find also crazy data like 4 or 7 millions).
By sure 1-million machine was produced in 1967. MC-24 was produced
until 1973. Then 1.5 million is an affordable estimate.
Another curious issue is the rate making/selling price. Beltrami,
Olivetti CEO, reported that in 1971 making cost was 30-35.000 Lire
whilst the machine was sold for 300.000 Lire!
A rate 1/10 is quite unusual. I suppose this is due to Capellaro's genial project. He reduced all frictions and stress to minimum. This allowed Olivetti to use cheap materials instead of special steel. The machine includes just a couple of (expansive) bearing rolls. Nevertheless the machine was strong and affordable. An old hardware shop near my institute is still using a Divisumma-24"