How can i judge 1st string position is correct number

[perfringo]

There is str.startswith() method which:

Output:
Return True if string starts with the prefix, otherwise return False. prefix can also be a tuple of prefixes to look for. With optional start, test string beginning at that position. With optional end, stop comparing string at that position.

So:

>>> my_string = '1100'                                                                     
>>> my_string.startswith('1')                                                              
True
>>> my_string.startswith('0')                                                              
False

You can see all the str methods by writing str. into interactive interpreter and pressing TAB two times:

>>> str.
str.capitalize(   str.index(        str.isspace(      str.replace(      str.strip(       
str.casefold(     str.isalnum(      str.istitle(      str.rfind(        str.swapcase(    
str.center(       str.isalpha(      str.isupper(      str.rindex(       str.title(       
str.count(        str.isascii(      str.join(         str.rjust(        str.translate(   
str.encode(       str.isdecimal(    str.ljust(        str.rpartition(   str.upper(       
str.endswith(     str.isdigit(      str.lower(        str.rsplit(       str.zfill(       
str.expandtabs(   str.isidentifier( str.lstrip(       str.rstrip(      
str.find(         str.islower(      str.maketrans(    str.split(       
str.format(       str.isnumeric(    str.mro(          str.splitlines(  
str.format_map(   str.isprintable(  str.partition(    str.startswith(

You can find what any of these methods do by using built-in help:

>>> help(str.capitalize)
Help on method_descriptor:

capitalize(self, /)
    Return a capitalized version of the string.
    
    More specifically, make the first character have upper case and the rest lower
    case.

Press Q to exit help.