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Vamshi Jandhyala

Books · Number Puzzles

Chapter 33

A Cube and a Square

Find two whole numbers such that the difference of their squares is a perfect cube, while the difference of their cubes is a perfect square.

Solution

The numbers 66 and 1010 do both at once: 10262=10036=64=43,10363=1000216=784=282.\begin{gathered} 10^2 - 6^2 = 100 - 36 = 64 = 4^3,\\ 10^3 - 6^3 = 1000 - 216 = 784 = 28^2. \end{gathered} The difference of the squares is the cube of 44, and the difference of the cubes is the square of 2828.