how many mm is a nickel coin
Nickel (United States coin) A nickel, in American usage, is a five-cent coin struck by the United States Mint. Composed of 75% copper and 25% nickel, the piece has been issued since 1866. Its diameter is .835 inches (21.21mm) and its thickness is .077 inches (1.95 mm). The silver half dime, equal to five cents, had been issued since the 1790s.