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MathNet 2013 Question 77

Math Olympiad Vault · MathNet 2013

Question 77

a) Show that $\frac12+\frac13+\frac14+\cdots+\frac1{2^m}\lt m$ for every positive integer $m$.

b) Let $p_1,p_2,\ldots,p_n$ be the primes less than $2^{100}$. Show that $\frac1{p_1}+\frac1{p_2}+\cdots+\frac1{p_n}\lt 10$.