Patent for am adding machine by using two disks, one a units-disk with pins in multiples of ten, one a tens-disk, is an annular disk with pin surrounding the units disk, an outwardly spring-pressed holder having a beveled outer end frictionally engaging the pins of the tens-disk and a carrier having oppositely-beveled ends engaged a supplemental pin and one pin on the tens-disks, teeth in the adjacent faces of the holder and carrier, and an idle-gear between them to enable the adding operation. (Lines 50-62) Illustration is included.