The cube of 0.5 is:

1. 1.25

2. 0.125

3. 12.5

4. 0.0125

The smallest number by which 72 must be multiplied to obtain a perfect cube is:

1. 3

2. 2

3. 4

4. 6

The smallest number by which 81 be divided to obtain a perfect cube is :

1. 1

2. 3

3. 9

4. none of the above

Find the cube of 7.