Assuming there are an infinite supply of coins, what is the fewest number of coins would be required in order to make sure each and every coin touched exactly three other coins?

Assuming there are an infinite supply of coins, what is the fewest number of coins would be required in order to make sure each and every coin touched exactly three other coins?

Four.

Damn.

You mean I got one right?

Yes, four, placed in a tetrahedron shape.

Rats! Too late!

Yes, you got one right. Maybe more than one. đź™‚

Can I see a picture please as I do not think it is possible using UK currency.

Try it for us and report your findings.