If a square has a side length of , then the area is . If a square has an area of , then the side length is . For a positive number , the square root of is defined as the positive number that squares to make , and it is written as . In other words, . We can also think of as a solution to the equation . This square has an area of because its sides have length : 

Similarly, if a cube has an edge length of , then the volume is . If a cube has a volume of , then the edge length is . The number is defined as the number that cubes to make . In other words, . We can also think of as a solution to the equation . This cube has a volume of because its sides have a length of :