Sharp pental mode

[ijabbott]

All the Sharp scientific/graphic calculators I've looked at that support hexadecimal, octal and binary also support "pental" (base 5). Do any other calculators support that (apart from the ones that support arbitrary bases)? Is there any practical use for it, or did they just add it for teaching purposes?

[Dave Britten]

Sharp is the only place I've ever seen it, and I think I remember reading that it makes sense in the context of certain abacus designs.

[ijabbott]

(04-17-2018 02:16 PM)Dave Britten Wrote:  Sharp is the only place I've ever seen it, and I think I remember reading that it makes sense in the context of certain abacus designs.

Now that you mention it, I recall that Japanese abacuses (abaci?) are sort of base 5 + base 2 in that each decimal digit is split into 4 beads to count 0, 1, 2, 3, 4, plus another bead to count 0, 5.

[Dave Britten]

Sharp even made a few hybrid devices, so that's probably the most likely explanation.

http://retrocalculators.com/digicus.htm