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 ...

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 ...

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 ...

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 ...

This lively journal is produced five times per year and includes contributions from mathematics practitioners. It reflects the best of current thinking and practice. In addition to articles covering ...