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Mathematics

Mathematician cracks centuries-old problem about the number 33

By Donna Lu

14 March 2019

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The number 33 has surprising depth

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Add three cubed numbers, and what do you get? It is a question that has puzzled mathematicians for centuries.

In 1825, a mathematician known as S. Ryley proved that any fraction could be represented as the sum of three cubes of fractions. In the 1950s, mathematician Louis Mordell asked whether the same could be done for integers, or whole numbers. In other words, are there integers k, x, y and z such that k = x3 + y3 + z3 for each possible value …

Article amended on 1 April 2019

We clarified the statement of Louis Mordell’s question

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