How to find an x-digit number in a text?

Question

Is there a better (more efficient) way to find x-digit number (number consisted of x digits) in a text?

My way:

EDIT:

for n in range(0,len(text)):
    if  isinstance(text[n:n+x], (int)) and isinstance(text[n:n+x+1] is False:
        result = text[n:n+x]

return result

EDIT 2:

for n in range(0,len(text)):
    try:  
       int(text[n:n+x])
       result = text[n:n+x]
    except:
       pass

return result

Answer 1

import re                                             
string = "hello 123 world 5678 897 word"              
number_length = 3                                     
pattern= r"\D(\d{%d})\D" % number_length   # \D to avoid matching 567           
print re.findall(pattern, string)

output

["123","897"]