S_{1} = 4 \cdot 3 {cm}^{2} = 12 {cm}^{2} = 0, 0012 m^{2}

${S_1 = 4 \cdot 3\, \text{cm}^2 = 12\, \text{cm}^2 = 0,0012 \,\text{m}^2}$

Error