Python Number to Ordinal

def Ordinal(Num):
    Num = str(Num)
    if Num.endswith('1') and not Num.endswith('11'):
        return Num + 'st'
    elif Num.endswith('2') and not Num.endswith('12'):
        return Num + 'nd'
    elif Num.endswith('3') and not Num.endswith('13'):
        return Num + 'rd'
    else:
        return Num + 'th'