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.

The Numbers’ Dress-up Party

All the numbers have come to a dress-up party in full costume. They all know themselves which costume everyone else

Read more.Book-ended Sixes

Find the smallest number n, such that n ends in a 6, and when n is multiplied by 4 it

Read more.Making Forty

Use all of these symbols and only these symbols to produce the number 40: (())xxx+++3331111 **Extension** - What is the

Read more.Hexagon in a Circle

Hexagon with verticies on a circle has three consecutive sides 3 and three consecutive sides 5. What is the area

Read more.Consecutive Integers

Three consecutive integers are multiplied together, and the middle number is added to the total. E.g. Prove that this is

Read more.Puzzlebomb 55

Fill the grid with the numbers 1-35, using the clues given, so that each row contains 7 numbers each with

Read more.