Java console calculator
You do "the same" for all four choices - time to abstract!

import java.util.Scanner;    //imports scanners

public class Calc {

    enum Op {

        ADD("a", "add", "added to"),
        SUB("s", "subtract", "subtracted by"),
        MUL("m", "multiply", "multiplied by"),
        DIV("d", "divide", "divided by");
        public String key;
        public String command;
        public String result;

        Op(String key, String command, String result) {
            this.key = key;
            this.command = command;
            this.result = result;
        }

        public int eval(int x, int y) {
            switch (this) {
                case ADD:
                    return x + y;
                case SUB:
                    return x - y;
                case MUL:
                    return x * y;
                case DIV:
                    return x / y;
                default:
                    throw new AssertionError();
            }
        }
    }

    public static void main(String[] args) {
        while (true) //creates loop to top
        {
            System.out.println("Hello this is my calculator!");
            System.out.println("To add, type a, to subtract, type s.");
            System.out.println("To multiply, type m, to divide, type d.");

            Scanner scan = new Scanner(System.in);    //sets up scanners
            Scanner scan1 = new Scanner(System.in);


            String action = scan.nextLine();    //tells comp. to take user input

            Op op = null;
            for (Op operation : Op.values()) {
                if (operation.key.equals(action)) {
                    op = operation;
                    break;
                }
            }

            if (op != null) {
                System.out.println("Now type in the first number you would like to " + op.command + ".");
                int x = scan.nextInt();
                System.out.println("Now type the second number.");
                int y = scan.nextInt();
                int z = op.eval(x, y);
                System.out.println(x + " " + op.result + " " + x + " equals " + z + "!");
            }

            System.out.println("Would you like to start over? (yes,no)");
            String startOver = scan1.nextLine();

            if ("no".equals(startOver)) {
                System.out.println("Bye");
                return;
            }
        }
    }
}


So all operation specific information is captured in the Op enums. If you want to add other operations like min, max, and, or, xor or mod, you don't have to introduce new if-blocks, just new enums.