John D. Cook
@johndcook.bsky.social
Mathematician, data privacy consultant
See also @johndcook.mathstodon.xyz.ap.brid.gy
See also @johndcook.mathstodon.xyz.ap.brid.gy
September 24, 2025 at 3:10 PM
August 5, 2025 at 1:04 PM
March 17, 2025 at 1:28 AM
March 9, 2025 at 2:20 PM
February 13, 2025 at 12:56 PM
Does DeepSeek demonstrate that we don’t need as much compute power as we thought?
www.johndcook.com/blog/2025/02...
www.johndcook.com/blog/2025/02...
February 3, 2025 at 8:04 PM
Does DeepSeek demonstrate that we don’t need as much compute power as we thought?
www.johndcook.com/blog/2025/02...
www.johndcook.com/blog/2025/02...
How the day of the week for New Years Day goes through a 28 year cycle.
The green diamonds represent leap years and the blue squares represent ordinary years.
The green diamonds represent leap years and the blue squares represent ordinary years.
January 1, 2025 at 3:22 AM
How the day of the week for New Years Day goes through a 28 year cycle.
The green diamonds represent leap years and the blue squares represent ordinary years.
The green diamonds represent leap years and the blue squares represent ordinary years.
December 31, 2024 at 1:08 AM
Centered triangular numbers are the number of dots in images such as the one below.
The nth centered triangular number equals 1 + 3n(n + 1)/2.
The nth centered triangular number equals 1 + 3n(n + 1)/2.
December 25, 2024 at 3:47 PM
Centered triangular numbers are the number of dots in images such as the one below.
The nth centered triangular number equals 1 + 3n(n + 1)/2.
The nth centered triangular number equals 1 + 3n(n + 1)/2.
December 19, 2024 at 4:13 PM
If you press the cosine key on a calculator over and over, you always get stuck on the same number.
This post takes a more sophisticated look at a child’s amusement.
www.johndcook.com/blog/2024/12...
This post takes a more sophisticated look at a child’s amusement.
www.johndcook.com/blog/2024/12...
December 17, 2024 at 6:05 PM
If you press the cosine key on a calculator over and over, you always get stuck on the same number.
This post takes a more sophisticated look at a child’s amusement.
www.johndcook.com/blog/2024/12...
This post takes a more sophisticated look at a child’s amusement.
www.johndcook.com/blog/2024/12...
A golden hospital gown is an allusion to The Emperor’s New Clothes, except the emperor is somewhere between sumptuously clothed and naked.
www.johndcook.com/blog/2024/12...
www.johndcook.com/blog/2024/12...
December 16, 2024 at 1:10 PM
A golden hospital gown is an allusion to The Emperor’s New Clothes, except the emperor is somewhere between sumptuously clothed and naked.
www.johndcook.com/blog/2024/12...
www.johndcook.com/blog/2024/12...
How many ways can you select six points in the plane so that every subset of three points forms the vertices of an isosceles triangle?
www.johndcook.com/blog/2024/12...
www.johndcook.com/blog/2024/12...
December 9, 2024 at 2:17 PM
How many ways can you select six points in the plane so that every subset of three points forms the vertices of an isosceles triangle?
www.johndcook.com/blog/2024/12...
www.johndcook.com/blog/2024/12...
December 7, 2024 at 7:58 PM
December 3, 2024 at 10:58 PM
Number of elements in the nth row of the periodic table.
November 29, 2024 at 7:57 PM
Number of elements in the nth row of the periodic table.
November 29, 2024 at 4:04 PM
November 28, 2024 at 2:01 PM
November 28, 2024 at 1:19 PM
November 27, 2024 at 9:48 PM
November 26, 2024 at 1:43 PM
November 26, 2024 at 3:09 AM