Multiple choice

What is the minimum possible sum of digits of X, if the LCM of natural numbers X and Y is 665? (Given X > Y)

  1. 1

  2. 3

  3. 5

  4. 7

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The LCM of X and Y is 665. The prime factorization of 665 is 5 * 7 * 19. Since X > Y and LCM(X, Y) = 665, X must be a factor of 665. Possible values for X are 665, 133, 95, 35. The sum of digits for 665 is 17, for 133 is 7, for 95 is 14, and for 35 is 8. The minimum sum is 7.