How many bricks, each measuring 25 cm x 11.25 cm x 6 cm, will be needed to build a wall of 9 m x 6 m x 22.5 cm?  Choose the correct choice from the following:  A) 6400  B) 6410  C) 6440  D) 7200  E) 6800

Rationale: "number of bricks = volume of wall / volume of bricks = 900 x 600 x 22.5 / 25 x 11.25 x 6 = = 7200 answer : d"
Answer: D