For example, if you measure the sides of a rectangular piece of metal as 120.3 mm and 83.3 mm and use a calculator to calculate the area as 10 010.99 mm2, how certain are you that the actual area is this value and would it be better to quote that area as 10 011 mm2? If you measure the voltage across a resistor as 4.3 V and the current through it as 0.33 A and use a calculator to determine the resistance, i.e. the value of voltage/ current, as 13.03030303 Ω, how many decimal place figures should you be quoting?