The first four triangular numbers are 1, 3, 6 and 10, and the nth triangular number is given by the expression n(n+1)/2, so the 20th such number is 20 × 21 ÷ 2 = 210. ENIGMA is a triangular ...

https://doi.org/10.4169/college.math.j.46.3.172 https://www.jstor.org/stable/10.4169/college.math.j.46.3.172 The College Mathematics Journal emphasizes the first two ...

Harry and Tom have each found a 4-digit perfect square, a 3-digit perfect cube and a 3-digit triangular number that use 10 different digits, but with no leading zero. A triangular number is one that ...

Pascal’s triangle is one of the most famous of all mathematical diagrams, simple to construct and yet rich in mathematical patterns. These can be found by a web search, but their discovery by study of ...

The Mathematical Gazette is the original journal of the Mathematical Association and it is now over a century old. Its readership is a mixture of school teachers, college and university lecturers, ...