You may have multiplied 4 feet by $\displaystyle\frac{{{3}\ \text{ inches}}}{{{1}\ \text{ foot}}}\usepackage{cmbright}\Huge\$ and then added 10 inches. You need to multiply 4 feet by $\displaystyle\frac{{{12}\ \text{ inches}}}{{{1}\ \text{ foot}}}\usepackage{cmbright}\Huge\$ and then add 10 inches.