A hall 36m long and 15m broad is to be paved with stones, each measuring 6dm by 5 dm. The number of stones required is:  Select the correct option:  A) 180  B) 1800  C) 18  D) 18000  E) 1.8

Rationale: "area of the hall = 3600 * 1500 area of each stone = ( 60 * 50 ) therefore , number of stones = ( 3600 * 1500 / 60 * 50 ) = 1800 answer : b"
Answer: B