We’re rewarding the question askers & reputations are being recalculated! Read more.

 177 Find five positive integers whose reciprocals sum to $1$ 22 Is 'no solution' the same as 'undefined'? 9 A year having more than one Friday the 13th? 9 Does 17% have to be equal to 0.17? 8 What does $\forall x \exists y(x + y = 0)$ mean?

### Reputation (6,061)

 +10 Find five positive integers whose reciprocals sum to $1$ +10 Simple geometry question, to be proved without trigonometry +10 A year having more than one Friday the 13th? +10 Why does the Cauchy distribution have no mean if it's symmetric around 0?

### Questions (34)

 71 What's a proof that the angles of a triangle add up to 180°? 23 What is the next perfect square of the form 14444… in decimal notation? 14 The Ellipse Problem - finding an ellipse inside a triangle 11 Why does the Cauchy distribution have no mean if it's symmetric around 0? 10 Is there a function such that $f(f(n)) = 2^n$?

### Tags (84)

 186 elementary-number-theory × 6 27 arithmetic × 4 178 diophantine-equations × 2 24 soft-question × 6 177 fractions 22 terminology × 2 177 egyptian-fractions 17 number-theory × 6 27 probability × 13 13 statistics × 12