Question

whats the capacity of a 3 cubic foot carton in cubic inches

Answer 1

$3ft^{3}$

$1ft = 12 inches$

$1^{3}ft^{3} = 12^{3} inches^{3}$

and 

$1ft ^{3} = 1728inches^{3}$

meaning that 

$3ft^{3} = 3 * 1728 inches^{3}$

finally 

$3ft^{3} = 5184 inches^{3}$