$6$ centimeters are equal to how many millimeters?

Hint: In this question we have been asked to convert centimeters into millimeters. In order to be able to answer this question, you must be aware about the chart of measure of length. Then, you must know when to multiply or when to divide. After studying about these facts, convert the value given in the question.

Complete step-by-step answer:
We have been asked to convert $6$ centimeters into millimeters.
What relation to use while converting the values?
We know that $1cm = 10mm$.
We have to find out about $6cm$.
So, we will multiply $6$ by $10$.
$ \Rightarrow 6cm = 6 \times 10mm$
Hence, $6cm = 60mm$

Thus, we got the required answer.

Note:
 Let us find out how many measures of length are there.
 There are $7$ measures of length. Starting with the largest, they are:
1) Kilometer
2) Hectometer
3) Decameter
4) Meter
5) Decimeter
6) Centimeter
7) Millimeter
These are not available only to measure length. But these are also available to measure other quantities also. We can use these prefixes to measure other quantities. For example: kiloliters, hectoliters, decaliters, liters, deciliters, centiliters and milliliters. Hence, these are just the prefixes. You can also use them to measure weight.
Now, how to know whether we have to multiply or we have to divide?
When we move from a smaller quantity to a bigger quantity, we multiply by $10$ as each quantity increases by $10$ times. On the other hand, when we move from a bigger quantity to a smaller quantity, we divide by $10$ as each quantity decreases by $10$ times.