So for my chem class, I have to measure a notebook, a pencil, a regular house key, a calculator, and a pair of scissors

I have to use a centimeter ruler that goes from 0-14 cm

I have to use a centimeter ruler that goes from 0-140 cm

I have to use a millimeter ruler that goes from 0-140 mm

then I have to answer this question

Which ruler has the greatest precision?

please help, I need the exact measurements