Update 100+ Python challenging programming exercises for Python 3.md

Author: PistonUser

100+ Python challenging programming exercises for Python 3.md

@@ -563,12 +563,9 @@ Solution:
 
 ```python
 def putNumbers(n):
-    i = 0
-    while i<n:
-        j=i
-        i=i+1
-        if j%7==0:
-            yield j
+    for i in range(0,n):
+        if i%7==0:
+            yield i
 
 for i in reverse(100):
     print(i)