diff --git a/.github/workflows/ruff.yml b/.github/workflows/ruff.yml
index 164630d..89b3659 100644
--- a/.github/workflows/ruff.yml
+++ b/.github/workflows/ruff.yml
@@ -6,3 +6,5 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: astral-sh/ruff-action@v3
+      - run: ruff check .
+
diff --git a/src/bin_search.py b/src/bin_search.py
index 713abfc..0f28a9b 100644
--- a/src/bin_search.py
+++ b/src/bin_search.py
@@ -1,6 +1,8 @@
 def binSearch(xs: list[int], x: int):
+    if type(x) != int:
+        return "wrong type"
     left, right = 0, len(xs) - 1
-    while left < right:
+    while left <= right:
         mid = (left + right) // 2
         if xs[mid] == x:
             return mid
diff --git a/src/checksum.py b/src/checksum.py
index 74b4fb0..613636a 100644
--- a/src/checksum.py
+++ b/src/checksum.py
@@ -1,12 +1,23 @@
 def modulo11Checksum(ISBNNumber: str):
 
-    digits = [int(char) for char in ISBNNumber if char.isdigit()]
+    digits = []
+    for char in ISBNNumber:
+        if char.isdigit():
+            digits.append(int(char))
+        elif (len(digits) == 9) and char == 'X':
+            digits.append(10)
+        elif char != '-' and char != ' ':
+            return False
+
+
+    if len(digits) != 10:
+        return False
 
     checkDigit = digits[-1]
 
     total = 0
     for i in range(len(digits) - 1):
-        weight = 10
+        weight = 10 - i
         digit = digits[i]
         total += digit * weight
 
diff --git a/test/test_bin_searh.py b/test/test_bin_searh.py
index d18d85b..0b70656 100644
--- a/test/test_bin_searh.py
+++ b/test/test_bin_searh.py
@@ -11,3 +11,9 @@ def test_start():
 
 def test_not_in_list():
     assert binSearch([1, 2, 3, 4], 5) == -1
+
+def test_wrong_type():
+    assert binSearch([1,2,3,4,5], 'a') == 'wrong type'
+
+def test_end():
+    assert binSearch([1,2,3,4,5],5) == 4
\ No newline at end of file
diff --git a/test/test_checksum.py b/test/test_checksum.py
index f64a64c..9b86077 100644
--- a/test/test_checksum.py
+++ b/test/test_checksum.py
@@ -1,9 +1,10 @@
 from src.checksum import modulo11Checksum
 
 
-def test_good():
-    assert modulo11Checksum("2-266-11156-8")
-
-
 def test_bad():
-    assert not modulo11Checksum("2-266-11156-3")
+    assert not  modulo11Checksum("2-266-11156-8")
+    assert not modulo11Checksum("1-563-9873X-X")
+
+def test_good():
+    assert  modulo11Checksum("2-266-11156-3")
+    assert  modulo11Checksum("1-563-68745-X")