A Piece of the Pi: mathematics explained
Subscribe
Sign in
Home
Podcast
Notes
Chat
Advanced
Beginner
Bonus Content ➕
Browse By Topic
Archive
Leaderboard
About
Colouring identical cuboids
How many colours do we need to colour a fixed stack of identical cuboids with integer coordinates in such a way that no two cuboids of the same colour…
Dec 30, 2025
•
Richard Green
5
2
2
Modular curve stitching
Consider the points of a clock face, numbered 1 up to 12, and for each point k, draw a straight line between k and 2k, taking remainders modulo 12.
Dec 10, 2025
•
Richard Green
11
6
4
The poetry of Steiner systems
A Steiner triple system consists of a set S (such as the set of seven letters {A, E, H, R, T, W, Y}) together with a set of 3-element subsets of S…
Nov 14, 2025
•
Richard Green
8
15
2
Perfect difference sets and Sidon sets
Consider a wheel with 21 evenly spaced positions, consecutively numbered 0, 1, 2, up to 20, and highlight the positions 1, 2, 5, 15, and 17 in bold, as…
Oct 30, 2025
•
Richard Green
7
2
2
How many cylinders can touch each other?
In 1968, J.E.
Oct 13, 2025
•
Richard Green
7
1
2
Beginner Posts
View all
Colouring identical cuboids
How many colours do we need to colour a fixed stack of identical cuboids with integer coordinates in such a way that no two cuboids of the same colour…
Dec 30, 2025
•
Richard Green
5
2
2
Modular curve stitching
Consider the points of a clock face, numbered 1 up to 12, and for each point k, draw a straight line between k and 2k, taking remainders modulo 12.
Dec 10, 2025
•
Richard Green
11
6
4
Perfect difference sets and Sidon sets
Consider a wheel with 21 evenly spaced positions, consecutively numbered 0, 1, 2, up to 20, and highlight the positions 1, 2, 5, 15, and 17 in bold, as…
Oct 30, 2025
•
Richard Green
7
2
2
The golden ratio as a number base
The Fibonacci numbers (1, 1, 2, 3, 5, 8, 13, 21, 34, 55, …) are one of the most famous sequences of integers.
Sep 27, 2025
•
Richard Green
20
7
5
Spiral Sudoku
Suppose we have a 5×5 grid with 15 circled positions in a spiral shape as shown above.
Jul 23, 2025
•
Richard Green
10
5
1
Top posts
How to build a computer using origami
Sep 20, 2023
•
Richard Green
19
1
4
Chess and the number e
Dec 16, 2024
•
Richard Green
31
4
4
The geometry of musical keys
May 21, 2025
•
Richard Green
27
3
3
Curves and L-systems
Nov 3, 2023
•
Richard Green
16
4
2
Turning a triangle into a square
Jan 11, 2025
•
Richard Green
23
3
1
A Piece of the Pi: mathematics explained
For the intelligent general reader who likes mathematics.
Subscribe
Combinatorics 🧮
View all
Colouring identical cuboids
How many colours do we need to colour a fixed stack of identical cuboids with integer coordinates in such a way that no two cuboids of the same colour…
Dec 30, 2025
•
Richard Green
5
2
2
The poetry of Steiner systems
A Steiner triple system consists of a set S (such as the set of seven letters {A, E, H, R, T, W, Y}) together with a set of 3-element subsets of S…
Nov 14, 2025
•
Richard Green
8
15
2
How many cylinders can touch each other?
In 1968, J.E.
Oct 13, 2025
•
Richard Green
7
1
2
Matroid bingo
Matroid bingo is a simplified version of the game of bingo.
Sep 15, 2025
•
Richard Green
8
3
Transparent rectangle visibility graphs
A graph consists of a set of vertices, some of which are joined in pairs by edges.
Sep 1, 2025
•
Richard Green
5
5
1
Keep the posts coming!
Subscribe
This site requires JavaScript to run correctly. Please
turn on JavaScript
or unblock scripts
