As an example, consider the calculation of body mass index (BMI) and assessing whether a person is overweight. BMI is calculated as a person's body weight in kilograms divided by the square of their height in metres. A bathroom scale may have a resolution of one kilogram. Intermediate values cannot be discerned—79.6 kg and 80.3 kg are indistinguishable, for example—but the true weight is rounded to the nearest whole number. It is unlikely that when the scale reads 80 kg, the person weighs "exactly" 80.0 kg. In normal rounding to the nearest value, the scale's showing 80 kg indicates a weight between 79.5 kg and 80.5 kg. This corresponds with the interval formula_19.