Question: how many mm is a 20 cent coin?
Answer: It weighs 5.65 grams and is 23.60 millimetres in diameter. The reverse of the 20 cent coin features an image of a platypus which was designed by Stuart Devlin. This image has been used since 1966, but a number of commemorative designs have also been released. The coin is made of 75% copper and 25% nickel.