Volume measures the space inside a rectangular prism and can be interpreted as the number of unit cubes it contains: multiplying length, width, and height counts equal layers of cubes. A prism can also be decomposed into smaller rectangular prisms, with total volume found by adding their volumes; this connects multiplication and addition through the distributive property and applies to whole-number and fractional measurements without double-counting shared boundaries.
Volume tells how much space is inside a rectangular prism. If the prism is filled with unit cubes, its volume is the number of cubes inside:
You can also split a prism into smaller rectangular prisms. Find each smaller volume, then add them. This works because multiplication distributes over addition.
Example: A rectangular prism is units long, units wide, and units high. Find its volume by splitting it into two prisms.
Split the length of units into units.
Find the volume of the first prism:
So, the total volume is
This matches multiplying the full dimensions at once:
The connection is shown by
The shared dividing face is only a boundary, not extra space, so it is not counted twice.
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