I am trying to count the number of digits of an input. However, whenever I input 10 or 11 or any two digit number, the output is 325.
Your error mainly happened here:
countnumber=countnumber/10
Note that you are intending to do integer division. Single-slash division in Python 3 is always "float" or "real" division, which yields a float value and a decimal part if necessary.
Replace it with double-slash division, which is integer division: countnumber = countnumber // 10. Each time integer division is performed in this case, the rightmost digit is cut.
You also have to watch out if your input is 0. The number 0 is considered to be one digit, not zero.