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.

Oblique Cylinder
What is the net of an oblique cylinder, and what is its surface area?
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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
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Book-ended Sixes
Find the smallest number n, such that n ends in a 6, and when n is multiplied by 4 it
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Making Forty
Use all of these symbols and only these symbols to produce the number 40: (())xxx+++3331111 **Extension** - What is the
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Hexagon in a Circle
Hexagon with verticies on a circle has three consecutive sides 3 and three consecutive sides 5. What is the area
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Consecutive Integers
Three consecutive integers are multiplied together, and the middle number is added to the total. E.g. Prove that this is
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Function Fun
Suppose Evaluate
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n to the Five
Is $latex n^5 + 5^n $ ever prime?
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Angles on a Grid
Note: The big square is divided into nine small squares of equal size.
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Puzzlebomb 55
Fill the grid with the numbers 1-35, using the clues given, so that each row contains 7 numbers each with
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