I've seen this in terms of rolling one coin completely around another...it will rotate TWICE Reason: one circumference's worth will rotate it once, however this 'path' is not flat and is a circular path (ie the static coin) hence the second rotation

## alternative puzzle/ solution

I've seen this in terms of rolling one coin completely around another...it will rotate TWICE

Reason: one circumference's worth will rotate it once, however this 'path' is not flat and is a circular path (ie the static coin) hence the second rotation