AS PHYSICS H/W Measurment Basics.

A Length measured with a standard ruler is exactly 10cm. Record this correctly.

Are you talking about uncertaintyy?. Then I think you would write it with the uncertainty of the 0 placement and where you take the measurement. A normal ruler measures in mm so the uncertainty in your measurements is 0.5mm at 0 and the same where you measure. 0.5 +0.5 = 1mm

Therefore you write ( 100mm +- 1mm ).