The radical sign may be one of the stranger-looking mathematical symbols, but its strange looks should not fool anyone. The radical sign has a straightforward meaning.

The sign that is used when finding the square root or cube root, , is called the radical sign. A radical sign with no index number written in the notch indicates a square root. A square root can also be written with an index of , but usually the 2 is understood rather than expressly written. A radical sign with an index of 3 is written as , which indicates a cube root.

For example, to calculate the area of a square (in which all sides are equal), multiply the length of one side s by itself (squaring), so the area is s². If the area of a square is known but not the length of the side, the inverse of squaring will find the...