1 m² = 10,000 cm², so 4 m² = 40000 cm². Area units are squared, so convert both length directions; that is why 1 m² equals 10,000 cm². Area is measured in square units, so the conversion factor is squared: 1 m = 100 cm, therefore 1 m² = 100 × 100 = 10,000 cm². Multiply the number of square metres by 10,000 and keep cm² as the unit.