Please help! I have 20 minutes and i have no idea on this. I have so many more lessons to turn in. 6) Use any of the digits 1, 3, and 9 and the operation signs +, -, x, to write all the whole numbers from 1 through 13. Each digit can be expressed only once in each example. You can use other digits in the expression, but you must also use a 1, 3, or 9 at least once in each expression.