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Cube of a Number |
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When we cube a number or find the cube of a number, we multiply the number by itself twice.
For example, the cube of 3 is 27; that is, we multiply 3 by itself twice so that 3 x 3 x 3 = 27. To find the cube of 15, we multiply 15 by itself twice so that 15 x 15 x 15 = 3375. To cube 3.6, we multiply 3.6 times itself twice so that 3.6 x 3.6 x 3.6 = 46.656. And so on.
Why is multiplying a number by itself twice called cubing the number? A three-dimensional object with all angles of the object being 90 degrees or right angles is called an orthotope (the ortho part of the name denotes perpendicularity). An orthotope is also called a right rectangular prism, a rectangular cuboid, or a rectangular parallelepiped. Since the volume of such an object is obtained by multiplying its length times its width times its height, and since a cube is a special case of such an object whose length, width, and height are all the same, it follows that multiplying a number by itself twice is akin to finding the volume of a geometric figure called a cube, and so we say that multiplying a number by itself twice is cubing the number or finding the cube of the number.
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