diff --git a/blockchain/chinese_remainder_theorem.py b/blockchain/chinese_remainder_theorem.py
index b6a486f0b1ed..3e4b2b7b4f10 100644
--- a/blockchain/chinese_remainder_theorem.py
+++ b/blockchain/chinese_remainder_theorem.py
@@ -12,7 +12,7 @@
 
 
 # Extended Euclid
-def extended_euclid(a, b):
+def extended_euclid(a: int, b: int) -> (int, int):
     """
     >>> extended_euclid(10, 6)
     (-1, 2)
@@ -29,7 +29,7 @@ def extended_euclid(a, b):
 
 
 # Uses ExtendedEuclid to find inverses
-def chinese_remainder_theorem(n1, r1, n2, r2):
+def chinese_remainder_theorem(n1: int, r1: int, n2: int, r2: int) -> int:
     """
     >>> chinese_remainder_theorem(5,1,7,3)
     31
@@ -51,7 +51,7 @@ def chinese_remainder_theorem(n1, r1, n2, r2):
 # ----------SAME SOLUTION USING InvertModulo instead ExtendedEuclid----------------
 
 # This function find the inverses of a i.e., a^(-1)
-def invert_modulo(a, n):
+def invert_modulo(a: int, n: int) -> int:
     """
     >>> invert_modulo(2, 5)
     3
@@ -67,7 +67,7 @@ def invert_modulo(a, n):
 
 
 # Same a above using InvertingModulo
-def chinese_remainder_theorem2(n1, r1, n2, r2):
+def chinese_remainder_theorem2(n1: int, r1: int, n2: int, r2: int) -> int:
     """
     >>> chinese_remainder_theorem2(5,1,7,3)
     31
diff --git a/blockchain/diophantine_equation.py b/blockchain/diophantine_equation.py
index 751b0efb7227..a92c2a13cfd5 100644
--- a/blockchain/diophantine_equation.py
+++ b/blockchain/diophantine_equation.py
@@ -5,7 +5,7 @@
 # GCD ( Greatest Common Divisor ) or HCF ( Highest Common Factor )
 
 
-def diophantine(a, b, c):
+def diophantine(a: int, b: int, c: int) -> (int, int):
     """
     >>> diophantine(10,6,14)
     (-7.0, 14.0)
@@ -37,7 +37,7 @@ def diophantine(a, b, c):
 # n is the number of solution you want, n = 2 by default
 
 
-def diophantine_all_soln(a, b, c, n=2):
+def diophantine_all_soln(a: int, b: int, c: int, n: int = 2) -> None:
     """
     >>> diophantine_all_soln(10, 6, 14)
     -7.0 14.0
@@ -72,7 +72,7 @@ def diophantine_all_soln(a, b, c, n=2):
 # Euclid's Algorithm
 
 
-def greatest_common_divisor(a, b):
+def greatest_common_divisor(a: int, b: int) -> int:
     """
     >>> greatest_common_divisor(7,5)
     1
@@ -98,7 +98,7 @@ def greatest_common_divisor(a, b):
 # x and y, then d = gcd(a,b)
 
 
-def extended_gcd(a, b):
+def extended_gcd(a: int, b: int) -> (int, int, int):
     """
     >>> extended_gcd(10, 6)
     (2, -1, 2)
diff --git a/blockchain/modular_division.py b/blockchain/modular_division.py
index 8fcf6e37cbed..e012db28fab8 100644
--- a/blockchain/modular_division.py
+++ b/blockchain/modular_division.py
@@ -14,7 +14,7 @@
 # Uses ExtendedEuclid to find the inverse of a
 
 
-def modular_division(a, b, n):
+def modular_division(a: int, b: int, n: int) -> int:
     """
     >>> modular_division(4,8,5)
     2
@@ -33,7 +33,7 @@ def modular_division(a, b, n):
 
 
 # This function find the inverses of a i.e., a^(-1)
-def invert_modulo(a, n):
+def invert_modulo(a: int, n: int) -> int:
     """
     >>> invert_modulo(2, 5)
     3
@@ -51,7 +51,7 @@ def invert_modulo(a, n):
 # ------------------ Finding Modular division using invert_modulo -------------------
 
 # This function used the above inversion of a to find x = (b*a^(-1))mod n
-def modular_division2(a, b, n):
+def modular_division2(a: int, b: int, n: int) -> int:
     """
     >>> modular_division2(4,8,5)
     2
@@ -72,7 +72,7 @@ def modular_division2(a, b, n):
 # and y, then d = gcd(a,b)
 
 
-def extended_gcd(a, b):
+def extended_gcd(a: int, b: int) -> (int, int, int):
     """
      >>> extended_gcd(10, 6)
      (2, -1, 2)
@@ -99,7 +99,7 @@ def extended_gcd(a, b):
 
 
 # Extended Euclid
-def extended_euclid(a, b):
+def extended_euclid(a: int, b: int) -> (int, int):
     """
     >>> extended_euclid(10, 6)
     (-1, 2)
@@ -119,7 +119,7 @@ def extended_euclid(a, b):
 # Euclid's Algorithm
 
 
-def greatest_common_divisor(a, b):
+def greatest_common_divisor(a: int, b: int) -> int:
     """
     >>> greatest_common_divisor(7,5)
     1