# Proof Problem #3

If $$1 + 1/2 + 1/3 + .... + 1/100 = A/B$$ where gcd(A,B) = 1 then show that $$AB$$ isn't divisible by 5

Note by Dev Sharma
2 years, 9 months ago

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That's an interesting question. What have you tried? Is it obvious that A is not divisible by 5? Is it obvious that B is not divisible by 5?

Staff - 2 years, 8 months ago

sir, I am still trying

- 2 years, 8 months ago

oh i failed to try it

- 2 years, 7 months ago