Test your knowledge of taxicab geometry, triangular numbers, the golden ratio and more. Credit... Supported by By Steven Strogatz “Math, Revealed,” our four-part series exploring the ...

A triangular number is one that fits the formula n (n+1)/2, such as 1, 3, 6, 10, 15. Even if I told you Harry’s triangular number you would not be able to deduce with certainty which perfect ...

2) It is a triangular number, that is of the series 1,3,6,10,15 … 3) It is a cube, or a cube plus 3. 4) It may be written as a single-digit prime followed by a two-digit prime.

But it was triangular numbers that got the ball rolling in the first place. Sign up here for the weekly Science Times newsletter.