摘要： Cube digit pairsEach of the six faces on a cube has a different digit (0 to 9) written on it; the same is done to a second cube. By placing the two cu... 阅读全文

摘要： Roman numeralsFor a number written in Roman numerals to be considered valid there are basic rules which must be followed. Even though the rules allow ... 阅读全文

摘要： Product-sum numbersA natural number, N, that can be written as the sum and product of a given set of at least two natural numbers, {a1, a2, … , ak} is... 阅读全文