We are given that Addison wants to cut 21 centimeters of lace. The question asks us to convert 24 centimeters into millimeters. However, to do that, we need to know how many millimeters are in a centimeter. There are 10 millimeters in a centimeter. Since centimeters are larger, we will need to multiply. Therefore, 21 × 10 is 210 millimeters, and that is how many millimeters Addison wanted to cut. Hope this helped and have a phenomenal day!