How many nickels equal 4mm?

To convert millimeters to nickels, you first need to know that a nickel has a diameter of 21.21 mm. To find how many nickels equal 4 mm, you divide 4 mm by the diameter of a nickel: 4 mm ÷ 21.21 mm ≈ 0.188 nickels. Therefore, 4 mm is less than a single nickel.