Question

What is the sum of all positive integers r that satisfy
Lcm[r,700] = 7000

Answer 1

Hint : \[ab = \text{lcm}(a,b) \times \gcd(a,b) \]

Answer 2

8000
(1000, 7000)

Answer 3

Yep! how did you get that ?

Answer 4

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Answer 5

Note the prime factorizations $700=2^2 * 5^2 * 7 and 7000=2^3 * 5^3 * 7
1) 2^3 * 5^3 = 1000
2) 7*2^3*5^3= 7000