Convert a diameter in centimetres to girth measurement in inches
Conversion factor: Pi = 3.14159265359 one centimetre (cm) = 0.393700787401575 inches (in) 3.14159265359 * 0.393700787401575 = 1.2368475014133050430153425898331 1.2368475014133050430153425898331 / 4 = 0.30921187535332626075383564745828 1 centimetre diameter = 0.309 212 inches quarter girth