User contributions
- 19:28, 6 July 2015 (diff | hist) . . (-2) . . Ball-and-urn (→Reasoning (One of Several): i made a wrong previous edit)
- 19:11, 6 July 2015 (diff | hist) . . (+2) . . Ball-and-urn (→Reasoning (One of Several): the aops book says it is choose k-1, not k)
