Measurement, Errors, Data and Unit Conversion

1 μg = 10−3 × 1 mg, so 1000 μg is the same as 1 mg.

1 mg = 103 × 1 μg, so one thousandth of a milligram is the same as one microgram.

Because the mass is stated to one decimal place, the absolute error is ±0.05.

Micrograms are smaller than grams, so there will be more of them. A million times more, so 0.25 × 106 = 250,000 μg (g to μg: shift the decimal point six places to the right).

We know that 1 mmHg is the same as 0.133 kPa, so two of them would be 2 × 0.133 = 0.266 kPa. Hence 120 of them would be 120 × 0.133 = 16 kPa.