5. Is there a strictly increasing function $f:\mathbb{R}\to\mathbb{R}$ such that $f'(x)=f(f(x))$ for all $x?$

https://artofproblemsolving.com/community/c7h381045p2109524

6. Let $T$ be the set of all triples $(a,b,c)$ of positive integers for which there exist triangles with side lengths $a,b,c.$ Express \[\sum_{(a,b,c)\in T}\frac{2^a}{3^b5^c}\] as a rational number in lowest terms.

https://artofproblemsolving.com/community/c7h1171039p5624386

7. A hilarious integer is a positive integer whose digits in base $10$ are all ones. Find all polynomials $f$ with real coefficients such that if $n$ is hilarious, then so is $f(n)$.

https://artofproblemsolving.com/community/c7h177229p978388

8. Four points are chosen uniformly and independently at random in the interior of a given circle. Find the probability that they are the vertices of a convex quadrilateral.

https://artofproblemsolving.com/community/c7h122451p694692

9. https://artofproblemsolving.com/community/c7h513433p2882551

10. https://artofproblemsolving.com/community/c7h122452p694694

11. https://artofproblemsolving.com/community/c7h413599p2325325

12. https://artofproblemsolving.com/community/c7h466470p2612317

13. https://artofproblemsolving.com/community/c7h530478p3027460

14. https://artofproblemsolving.com/community/c7h20497p134592

15. https://artofproblemsolving.com/community/c7h469262p2626897

16. https://artofproblemsolving.com/community/c7h469256p2626877

17. https://artofproblemsolving.com/community/c7h429342p2429218

18. https://artofproblemsolving.com/community/c7h504348p2832941