A concrete slab is 5 m long, 2 m wide and 20 cm thick. Find its volume in cubic metres.

**Volume = length × breadth × height = $l\times b\times h$.**

For a cube: $V=s^3$.

Units: if $l,b,h$ are in cm, $V$ is in ${\text{cm}}^3$. If in $m,V$ is in $m^3$. **Always check units before computing.** Mixing $m$ and cm gives nonsense.

Example: cuboid $4\times 5\times 3$ cm. $V=60{\text{cm}}^3$. Cube of side 7 cm: $V=343{\text{cm}}^3$.