Surface area of hollow roll paper

The surface area of the hollow roll paper is equal to the lateral area of the cylinder multiplied by 2, plus the bottom area of the cylinder multiplied by 2, minus the area of the hollow circle multiplied by 2.

Hollow roll paper is a paper towel that can often be used in the family. Generally used in kitchens and bathrooms. The length of the roll paper needs to be determined by yourself, and then it is torn and used, which is relatively convenient to use.