I have a box that is 15cm-wide, 10cm-long, and 3cm- wide. To get it's volume I would add all the sides.

Thanks

No. To get its volume multiply the three dimensions together.

Actually, to find the volume of a box, you need to multiply the length, width, and height of the box. The formula for finding the volume of a rectangular box is:

Volume = Length × Width × Height

In your case, the length of the box is 15cm, the width is 10cm, and the height is 3cm. So, to find the volume, you would use the following calculation:

Volume = 15cm × 10cm × 3cm
= 450 cubic centimeters

Therefore, the volume of your box is 450 cubic centimeters.