A lady builds 7cm length, 18cm width, and 3cm height box using 9cubic cm cubes. What is the minimum number of cubes required to build the box? Choose the correct choice from the following:
A) 42	B) 45	C) 47	D) 49	E) 56

Rationale: number of cubes required = volume of box / volume of cube = 7 * 18 * 3 / 9 = 42 cubes answer : a
Answer: A