[tex]\displaystyle\bf\\7\frac{1}{3}~mm\times4\frac{1}{2}~mm=\\\\\\=\frac{7\times3+1}{3}\times\frac{4\times2+1}{2}=\\\\\\=\frac{21+1}{3}\times\frac{8+1}{2}=\\\\\\=\frac{22}{3}\times\frac{9}{2}=\\\\\\=\frac{22\times9}{3\times2}=\\\\\\=\frac{11\times3}{1\times1}=11\times3=\boxed{\bf33~mm^2}[/tex]
