Salutations!
If my pencil is 11 cm long how long would it be in millimeters?
To find out it in millimeters ---- you need to know the rule to convert it vice versa.
1cm = 10 mm
So, we know that centimeter is greater than millimeter. All you have to do is add a zero because we are multiplying them by 10.
11×10 = 110.
Thus, your answer would be 110 millimeters.
Hope I helped :D