# how can you tell if rulers are the right length?

I have two rulers from school and they are different sizes...you can’t trust anybody these days man

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• 3 months ago

It's the same, measures 12"

Some rulers start measuring at end-to-end (most wood & metal rulers) (if end is damaged then measurement will be wrong)

Others have a margin before units start measuring. (common type bought everywhere)

• Lv 7
4 months ago

one is inches, the other is centimeters.

nobody in the world still uses the imperial system but the U.S.. it's one of the few ways we are still behind.

• 4 months ago

You have just learned a lesson about metrics. The metric is the device or means used to measure things by. Not all metrics are created equal; so in science experiments, one has to be very careful about the measuring stick used to measure experimental results.

So what you need to do is calibrate your two rulers...find out which one, if either, is correct. Without going to a lot of expense and time, get a third ruler and match your two against the third one. If one of them matches you have two of three that matches and those two are likely correct. May not be, but I'd bet on it.

• Lôn
Lv 7
4 months ago

Do you expect a metre rule to be the same size as a 12" ruler?