Thread: divisor problem

The least common multiple of two numbers is 105 and the greatest common divisor is 5. Which of the following could be the sum of the numbers?

(A) 21 (B) 25 (C) 49 (D) 50 (E) 105

Originally Posted by sri340

The least common multiple of two numbers is 105 and the greatest common divisor is 5. Which of the following could be the sum of the numbers?

(A) 21 (B) 25 (C) 49 (D) 50 (E) 105

least common multiple 105 the prime divisors of 105 , 3,5,7 so our two numbers is multiples of this three numbers just
greatest common divisors 5 so say our numbers a,b
5 is a divisors of a,b , 3,7 in one of them not both say "a" same for "7"
so the cases for a,b

a= 5*3 = 15
b= 5*7 = 35
a+b = 50

a=5*3*7=105
b=5 =5
a+b = 110

so D) is the answer