To find the volume of a rectangular box, just follow these easy steps:

1. Measure the Size: First, you need to measure how long, wide, and tall the box is.

   • The length ($l$)
   • The width ($w$)
   • The height ($h$)

   Make sure you use the same type of measurement for all the sizes, like centimeters or meters.

2. Use the Volume Formula: To figure out the volume ($V$) of the box, use this simple formula: $V = l \times w \times h$

3. Do the Math: Now, multiply the three sizes together. For example, if:

   • $l = 5 \text{ cm}$
   • $w = 3 \text{ cm}$
   • $h = 4 \text{ cm}$

   You would calculate: $V = 5 \times 3 \times 4 = 60 \text{ cm}^3$

4. Understand the Result: The number you find is the volume, which tells you how much space is inside the box. This is shown in cubic units.

And that's it! Now you know how to find the volume of a rectangular prism.