Write the next sentence in this paragraph:

How to calculate cbm
Measure the sides of the carton.
You'll need to know the length, width, and height of the rectangular carton. Use a measuring stick to find all three distances and mark them down separately.

OPTIONS:
(A). For example, if the box contains rectangular cartons, you will find the length at the front. Alternatively, if you want the horizontal shipping containers, which are width-wise, you'll find the length of the border 2 times the length and height.;
(B). If the measurements on each measuring stick are separated by a number of inches (usually by 8 inches or 1.3 cm), you'll have a divided measurement in inches. Even though the measurement will represent more of a negative proportion, cbm is calculated based on the actual length and width of any two measurements.;
(C). Cbm is a measurement of volume, so you'll be using the standard volume formula for rectangular prisms. Example: calculate the cbm of a rectangular package with a length of 15 cm, a width of 10 cm, and a height of 8 cm.;
(D). Measure the outside of the carton and mark each measurement down. It's a good idea to use a measuring stick to mark each measurement down, so you don't lose track of how far along the box is.;
(C).