1) Use the \\t escape character to print out a noughts and crosses grid, as shown below in fig. 1
```java
System.out.println("|\\to\\t|\\t \\t|\\tx\\t|");
System.out.println("|\\t \\t|\\tx\\t|\\to\\t|");
System.out.println("|\\to\\t|\\tx\\t|\\to\\t|");
```
2) Prompt the user to enter their (name). Print out "Hello" (name) "I hope you're well"
```java
Scanner scan = new Scanner(System.in);
System.out.println("Enter your name");
String name = scan.nextLine();
System.out.println("Hello " + name + ". I hope you're well.");
```
3) Use Math.sqrt() to print out the square root of 20
```java
System.out.println(Math.sqrt(20));
```
4) Use Math.sqrt() to print out the square root of 20 to 2 decimal places
```java
double root = Math.round(Math.sqrt(20)\*100)/100d;
System.out.println(root);
```
5) Use Math.random() to print out a random integer between 5 and 10
```java
System.out.println((int)(Math.random()\*5)+5);
```
6) Use Math.pow() to print out 2 to the power of 8
```java
System.out.println(Math.pow(2,8));
```
7) Prompt the user to enter a (number). Print out "The square root of " (number) " is " (answer)
```java
Scanner scan = new Scanner(System.in);
System.out.println("Emter a number");
double num = scan.nextDouble();
System.out.println("The square root of " + num + " is " + Math.sqrt(num));
```
or
```java
Scanner scan = new Scanner(System.in);
System.out.println("Emter a number");
double num = scan.nextDouble();
System.out.format("The square root of %f is %f%n", num, Math.sqrt(num));
```
8) Prompt the user to enter two numbers. Print out the average of those numbers.
```java
Scanner scan = new Scanner(System.in);
System.out.println("Emter a number");
double num1 = scan.nextDouble();
System.out.println("Enter another number");
double num2 = scan.nextDouble();
double average = (num1 + num2)/2;
System.out.println("The average of " + num1 + " and " + num2 + " is " + average);
```
9) To work out your BMI, divide your weight in kilograms by your height in metres squared. In other words BMI = w / h\*h. Write a program that prompts the user to input their weight and height, and then outputs their BMI.
```java
Scanner scan = new Scanner(System.in);
System.out.println("Emter your weight in kilograms");
double weight = scan.nextDouble();
System.out.println("Enter your height in meters");
double height = scan.nextDouble();
double BMI = weight/(height\*height);
System.out.println("Your BMI is " + BMI);
```