Cube Root of 2. Double The Volume of A Cube. The Delian Problem Doubling the cube, also known as the Delian problem, is an ancient geometric problem. Given the edge of a cube, the problem requires the construction of the edge of a second cube whose volume is double that of the first. In algebraic terms, doubling a unit cube requires the construction of a line segment of length x, where x3 = 2; in other words, the cube root of two, means, what number, multiplied by itself 3 times, will give the a