The metric system is a decimal-friendly system. The Greek prefixes that it uses are all some power of 10 greater or smaller than the base unit that they modify. As such, the conversion from one metric unit to another involves the movement of a decimal point some number of places. Looked at another way, all conversions involve multiplying or dividing by 10 raised to some power.
 

To convert from meter to millimeter, you need to understand the relationship between the base unit and the milli- version of the unit. The conversion will include the movement of a decimal point; this movement should be equivalent to a mathematical operation involving a mulitplying or dividing factor. The Staircase Model presented in the graphic below should provide the background that you need to conduct the conversion  Study the graphic and then answer the question.