# 100! Factorial Puzzles

David Butler (@DavidKButlerUoA) of the Maths Learning Centre at the University of Adelaide runs a puzzle and games club called “One Hundred Factorial” (named after the first puzzle the club tackled – read more here).

Across the years, many of these puzzles have been shared through photos on Twitter using #100factorial. Here I aim to curate a list of all the puzzles that have been shared, with descriptions and possible solutions, eventually with some degree of organisation, to aid in finding puzzles quickly in the future.

Only Ones
Using any or all of the operations of addition, subtraction, multiplication, division and exponentiation (and brackets), and as many of
One Spot Dice
You have two blank 6-sided dice. You are allowed to choose any number of the twelve faces and draw exactly
Number of Letters
The numbers seven, eleven, fifteen, nineteen make a sequence where the numbers go up by 4 each time. But if
Lousy Labelling
Three boxes filled with lots of balls are on the table. One box is full of red balls, one is
Combo Cube
Eight cubes are marked with one dot on two opposite faces, two dots on two opposite faces and three dots
Convexity of Deltahedra
Claim: There is a convex deltahedron with every even number of faces from 4 to 20, except one. Investigating non-convex