I need help in math. okay so this is a question. How can I get the answer 13 using the number 4 only with any operations but you have to use the number 4 as low as possible. I got the equation ....

44/4 + radical 4 . u got a shorter way? also if you can give me the equations for the numbers 15,7,9. i got the equations but i wont the shortest one.

44/4 + radical 4 . u got a shorter way? also if you can give me the equations for the numbers 15,7,9. i got the equations but i wont the shortest one.