The length factor: 3.28084
One meter equals 3.28084 feet. It might seem like the same 3.28084 factor should apply directly to area and volume conversions too — but it doesn't, because area and volume measure more than one dimension at once.
Area: the length factor, squared
One square meter equals 10.76391 square feet — and 3.28084² works out to 10.7639, matching exactly. A square meter is a 1m × 1m square; converting each side to feet and multiplying gives 3.28084ft × 3.28084ft = 10.7639 sq ft, which is exactly the squared factor.
Volume: the length factor, cubed
One cubic meter equals 35.314667 cubic feet — and 3.28084³ works out to 35.3147, again matching exactly. A cubic meter is a 1m × 1m × 1m cube; converting each of the three dimensions gives 3.28084ft × 3.28084ft × 3.28084ft = 35.3147 cu ft.
The general rule
Whenever a unit describes N dimensions, its conversion factor is the underlying length factor raised to the power of N — length itself uses the factor as-is (power 1), area squares it (power 2), and volume cubes it (power 3). This is why area and volume conversion factors always look larger and less familiar than the simple length factor they're built from.