A ruler has markings as shown below. Stefan uses this ruler to measure the length of a metal rod. How many decimal places should his answer include?

Based on a ruler in centimeters, with ten divisions between each centimer mark, you will have marks at every 0.1 cm.

Then, the measure of the length of a metal rod should have 1 decimal place.

That decimal place means mlimiters, given that 1 mm = 0.1 cm.

Answer: 1 decimal place