# Powers

```
1public class Ex9 {
2 public static void main(String[] args) {
3 int alpha = 5;
4 double beta = Math.pow(5, 2);
5 System.out.println("5 to the power of 2 is " + beta);
6
7 int gamma = 5.5;
8 double delta = Math.pow(5.5, 2.2);
9 System.out.println("5.5 to the power of 2 is " + delta);
10
11 int epsilon = 10;
12 int zeta = (int) Math.pow(5, 2);
13 System.out.println("5 to the power of 2.2 is " + zeta);
14
15 int eta = 4;
16 double sqrt = Math.sqrt(4);
17 System.out.println("The square root of 4 is " + sqrt);
18
19 int theta = 5;
20 sqrt = Math.sqrt(5);
21 System.out.println("The square root of 5 is " + sqrt);
22 }
23}
```

### Explanation

In this exercise, we introduce the functions

`Math.pow()`

and`Math.sqrt()`

.`Math.pow()`

puts the first argument to the power of the second argument. It takes a double for both its arguments, hence why we can do`Math.pow(5.5, 2.2)`

. It's fine to put integers as its arguments, since integers can be implicitly cast to doubles.`Math.sqrt()`

takes one double as an argument, and returns its square root.`Math.pow()`

and`Math.sqrt()`

return doubles as well.If you want to store the values returned from

`Math.pow()`

and`Math.sqrt()`

as integers, as in line 13, then you must explicitly cast it by putting`(int)`

in front of the double you want to cast to an int. The reason that doubles aren't implicitly cast to integers is because doubles are more precise.

### Extension Programs

Use a for loop, to write a program that prints out all the numbers between 1 to 100, squared.

Use a for loop, to write a program that prints out 2 to the power of 1, 2 to the power of 2, all the way to 2 to the power of 16.

Given that momentum = mass * (velocity to the power of 2), write a program to calculate momentum given mass and velocity. You will need to store mass and velocity as variables, and calculate momentum from the variables.

Write a program to calculate BMI (Body Mass Index) using the formula: BMI = mass / (height to the power of 2). You will need to store mass and height as variables, and calculate BMI from the variables.