Largest Possible GCD of 7 Distinct Integers

XAT 2023 · Quantitative Ability & Data Interpretation · Medium · Number System

The addition of 7 distinct positive integers is 1740. What is the largest possible "greatest common divisor" of these 7 distinct positive integers?

  1. A.

    42

  2. B.

    60

  3. C.

    74

  4. D.

    140

  5. E.

    None of the above.

Answer

B

Explanation

Let the 7 distinct integers be ma1,ma2,…,ma7m a_1, m a_2, \dots, m a_7 where mm is GCD. m(a1+a2+⋯+a7)=1740m(a_1 + a_2 + \dots + a_7) = 1740. Minimum sum of 7 distinct positive integers 1+2+3+4+5+6+7=281+2+3+4+5+6+7 = 28. Next smallest distinct sum = 1+2+3+4+5+6+8=291+2+3+4+5+6+8 = 29. 1740=60×291740 = 60 \times 29. Since 29 is prime, m=60m = 60 is the maximum GCD.

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