A centimetre is a unit that measures distance, or length. A centimetre is 1/100th of a meter and is abbreviated "cm." A millimetre measures 1/1000th of a meter. The abbreviation for millimetre is "mm." Transitioning from one to the other is straightforward.
Use your pencil to write the word "Legend" in the top-centre of your paper. Move to the next line below and write: "1.0 centimetre (cm) = 10.0 millimetres (mm); shift the decimal point one digit to the right." Draw a straight line under the "Legend" section separating it from the body of the paper and use it as a reference.
Move below the "Legend" and write your centimetre measurement, and then add a decimal point and zero, if it does not have one. For example, if you are converting "15 cm," write "15.0." If your measurement already has a decimal, write it down without the unit: "15.75."
Erase the decimal from its current position. Count one digit over and place decimal at the end: "15.0" converts to "150.0." Add a zero after at the end to avoid a hanging decimal. Also add the necessary commas to signify thousands and millions, if necessary.
Add the millimetre unit of measurement to your conversion: "150.0 mm" or "157.5 mm."
Type in your numerical measurement, without the unit: "15" or "15.75."
Multiply by 10. There are 10 millimetres in 1 centimetre.
The calculator will show "150.0" or "157.5." Note your final conversion as "150 mm" or "157.5 mm" on paper.
Simplify the conversion by using an online conversion calculator. Use the keywords "convert measurement calculator" in your favourite search engine to find a website. One such website is Google's "Calculator."