Calculate ratios for the number of centimeters in an inch and the number of inches in a centimeter: cm/in or

One inch is exactly 2.54 centimeters, so the ratio in centimeters per inch (cm/in) is 2.54. The reverse ratio, inches per centimeter (in/cm), is the reciprocal: 1 ÷ 2.54 ≈ 0.394.

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