Coin with the most sides

The coin that I have with the most sides is a 1993 Riyal from Yemen. It has 21 sides [referred to on Numista as Henicosagonal (21-sided)]. There are other varieties from Yemen that also have 21 sides.

This could be an interesting topic. How many sides can a coin have? I would assume there is some mathematical or geometric formula that can determine this. Say, as the size of a coins increases then the possibility of the number of sides increases. An increase in sides is directly proportional to the size or diameter of the coin. Something like that I guess...

What about the scalloped coins? how many sides do they count as?

Brazil 2,000 Réis 1937-8 KM# 548 has 24 sides (icosikaitetragonal)

https://www.ngccoin.com/price-guide/world/brazil-2000-reis-km-548-1937-1938-cuid-14831-duid-49403

Citeer: "neilithic"​What about the scalloped coins? how many sides do they count as?
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​Good point, as they say in geometry.

If you want to go to the extreme ... a circle has an endless amount of sides

Citeer: "Idolenz"​If you want to go to the extreme ... a circle has an endless amount of sides

​Spoken by a true mathematician, but I don't know the first thing about the calculus or how much it can be applied to coins. But it looks like 24 is tops at the moment.

And how about moving to the y-axis?
Which coin has the most sides in 3D?
Thou I don't consider them coins but catalogs include them as such. So; any mentions?
Also, for the flat coins I think there are several map-shaped ones that have a LOT of sides.

A circle has two sides.....an inside and an outside

Greetings...erdvilla. I was wondering where you were at.

I really think we should stick to the simple definition on sides (also remember that coins are not perfect circles).

France KM#856, 25 centimes 1904-05 has 22 sides, which makes it second after Houseofham's Brazil KM#548 2000 Réis 1937-38.

The common garden variety Australian 50 cent is 12 sided (Dodecagonal) ..... here is an example

However some of them are 14 sided (Tetra-Decagonal) ..... here is an example


Just thought members might be interested in that little known fact.

Cheers Mike