How many cubes of 3 cm edge be cut out of a cube of 18 cm edge?

Let the number of cubes that can be cut from bigger cube = n. Then,
n x Volume of smaller cube = Volume of bigger cube
Edge of smaller cube = 3 cm
Edge of bigger cube = 18 cm
n x (3)³ = (18)³
⇒ n = (18 x 18 x 18) / (3 x 3 x 3)
∴ n = 6 x 6 x 6 = 216 cubes