Having two standards for a keypad layout is inconvenient!  
Computer keypad's layout:  
Cell phone keypad's layout:  
Solve the horror of unstandartized keypads by providing a function that converts computer input to a number as if it was typed by a phone.
Example:  
"789" -> "123"
Notes:  
You get a string with numbers only
def computer_to_phone(numbers):
    pad = {
        "7":"1",
        "8":"2",
        "9":"3",
        "4":"4",
        "5":"5",
        "6":"6",
        "1":"7",
        "2":"8",
        "3":"9",
        "0":"0"
    }
    return "".join([pad[number] for number in numbers])
def computer_to_phone(numbers):
    pad = {
        "7":"1",
        "8":"2",
        "9":"3",
        "4":"4",
        "5":"5",
        "6":"6",
        "1":"7",
        "2":"8",
        "3":"9",
        "0":"0"
    }
    return "".join([pad[number] for number in numbers])