Question: what is the least common multiple of two numbers if one number is a multiple of the other?
Answer: The least common multiple of two numbers can be found by multiplying one of the numbers by the prime factors of the other number that the two numbers don't have in common. We can multiply 48 by 5 (the only prime factor of 40 not shared by 48), or we can multiply 40 by 2*3. Either way, we'll get 240.