A measurement is read to the nearest 0.001 m. If the observed value is 1.2345 m, what is the properly recorded value?

A measurement is read to the nearest 0.001 m. If the observed value is 1.2345 m, what is the properly recorded value?

• A. 1.234 m
• B. 1.2345 m
• C. 1.235 m
• D. 1.236 m

Answer: (C)

Rounding to the nearest 0.001 m means keep three decimal places. The observed value 1.2345 m has digits after the decimal as 2, 3, 4, 5. The third decimal (the thousandths place) is 4, and the next digit is 5, so we round that 4 up to 5. This gives 1.235 m. If you had truncated, you’d keep 1.234 m, but rounding requires increasing the thousandths when the next digit is 5 or more.

Rounding to the nearest 0.001 m means keep three decimal places. The observed value 1.2345 m has digits after the decimal as 2, 3, 4, 5. The third decimal (the thousandths place) is 4, and the next digit is 5, so we round that 4 up to 5. This gives 1.235 m. If you had truncated, you’d keep 1.234 m, but rounding requires increasing the thousandths when the next digit is 5 or more.