Final answer:
To convert centimeters to millimeters, multiply the number of centimeters by 10.
Step-by-step explanation:
To convert centimeters to millimeters, you need to multiply the number of centimeters by 10. This is because there are 10 millimeters in 1 centimeter.
So, to find out how many millimeters are in 4.2 centimeters, multiply 4.2 by 10.
4.2 centimeters x 10 = 42 millimeters
Learn more about Converting units from centimeters to millimeters