Just a simple tool for addition/subtraction/multiplication/division sums. Instructions: Enter the first number of your sum (e.g if you wanted to work out 9 * 21 you would enter 9) That number will appear on the calculator image. Enter the operation for your sum: addition, subtraction, multiplication or division. Enter using symbols: +, -, * and /. Enter the final number in the sum (e.g for 9 * 21 we would put 21) That number should now appear. After a few seconds you will have the answer.