Cool proofs, facts, objects
Physics / Calculations

Games
 Drommels (via Fred Horn)
 Parallelograms (via Fred Horn)
 Product
 CoNeutron
 Xonly TicTacToe
Puzzles
 Assassins
 Circle dissection
 12 face fully symmetric solid (via Nick or John)
 Flipping Ice Cream cake (via John McLeod)
 Set of sets of N, sum = 20, product maximum
 Four coins to line, six coins to hexagon
 2 = 4
 Hole in disk : dissection
 Rotation, Reflection, Translation
 2 of 1 kg balanced
 Peter Higgins' friend's daughter
 Josh's polynomial problem
 10x10 board, 41 rooks, find five that don't attack
 Maximise volume of cuboid if Length + circumference = 100
 Tile 8x8 with 2x1, is there necessarily a 2x2?
 Three litre, five litre
 1, 2, 5, 10 minutes  limit of 17
 My oldest plays the piano
