diff --git a/has_only_digits.py b/has_only_digits.py
index 4d95223..6481526 100644
--- a/has_only_digits.py
+++ b/has_only_digits.py
@@ -1,18 +1,16 @@
-# Given a string, check if it only contains digits
+# Given a string, check if it only contains digits.
 
 def is_digit(input_str):
-  digits = dict()
-
-  for char in input_str:
-    if char in digits:
-      digits[char] += 1
-    else:
-      digits[char] = 1
-  
-  if sum(digits.values()) == len(input_str):
-    return True
-  else:
-    return False
+    try:
+        # If its possible to convert to a number, return True.
+        int(input_str)
+        return True
+    except ValueError:
+        # If the string contains letters, above will fail, returning False.
+        return False
 
 result = is_digit("095357973590759530")
 print(result)  # True
+
+result = is_digit("1234abc567")
+print(result)  # False