diff --git a/polynomial.py b/polynomial.py
index 0450f2ef065d121a0b154683da3ed70636288456..6268848d8e8baf08a6e51d221ff69c390fa5ba33 100644
--- a/polynomial.py
+++ b/polynomial.py
@@ -121,6 +121,19 @@ def compute_bachet_bezout(a, b):
     return x[-1], y[-1]
 
 
+def modular_inverse(a, n):
+    res = -1
+    inverse = -1
+    i = 0
+    while res != 1:
+        if a * i % n == 1:
+            res = a * i % n
+            inverse = i
+            break
+        i += 1
+    return inverse
+
+
 def compute_lagrange_polynomial(points, prime_number):
     pass
 
@@ -145,6 +158,11 @@ def main():
     print("Pour les chiffres " + str(a) + " et " + str(b) +
           ". Les coéfficients de Bachet-Bézout sont : " + str(x) + " et " + str(y))
 
+    a = 3
+    b = 7
+    print("Inverse modulaire de " + str(a) + " % " +
+          str(b) + " est " + str(modular_inverse(a, b)))
+
     with open("messages.json") as f:
         messages = json.load(f)
     print(len(messages))