Result: 21 millimeters is about 53/64 of an inch.
The answer is 53/64 inch. The result is sometimes only an approximation of the real value because of rounding. But it's accurate enough for typical everyday measurements.
To convert 21 millimeters to an inch fraction, you need to first convert 21 millimeters to inches. Since 1 inch is equal to 25.4 millimeters, divide 21 by 25.4 to get decimal inches:
21 mm ÷ 25.4 = 0.8267 in
Then, let's convert the decimal value of 0.8267 inches to a fraction.
To convert 0.8267 inches to a fraction, use a ruler or a decimal to fraction conversion table to find the nearest fraction with a reasonable denominator (fractional inches usually have denominators that are powers of 2, such as 2, 4, 8, 16, 32, 64).
In this example, use a ruler to find the closest fraction.
Using a ruler, you can see that 0.8267 inches is very close to 53/64 inch.
Therefore, 21 millimeters is approximately equal to 53/64 inch.