diff --git a/mapytex/calculus/core/typing/add.py b/mapytex/calculus/core/typing/add.py
index 9e6ae54..a639515 100644
--- a/mapytex/calculus/core/typing/add.py
+++ b/mapytex/calculus/core/typing/add.py
@@ -42,7 +42,7 @@ def moscalar_mostr(left, right):
     return MOpolynomial(right, [left, 1])
 
 @add.register(MOstr, (MOnumber, MOFraction))
-def moscalar_mostr(left, right):
+def mostr_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
     >>> a = MOstr('x')
@@ -56,7 +56,7 @@ def moscalar_mostr(left, right):
     return MOpolynomial(left, [right, 1])
 
 @add.register((MOnumber, MOFraction), MOstrPower)
-def moscalar_mostr(left, right):
+def moscalar_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
     >>> a = MOnumber(2)
@@ -70,7 +70,7 @@ def moscalar_mostr(left, right):
     return MOpolynomial(right.variable, {0: left, right.power: 1})
 
 @add.register(MOstrPower, (MOnumber, MOFraction))
-def moscalar_mostr(left, right):
+def mostrpower_moscalar(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
     >>> a = MOstrPower('x', 3)
@@ -128,7 +128,10 @@ def moscalar_mopolynomial(left, right):
     >>> add(a, b)
     <MOpolynomial 1 / 5 + 3x^2 + 2x>
     """
-    new_coefs = right.coefficients
+    if 0 in right.coefficients.keys():
+        raise NotImplementedError(f"Polynomial with constant ({right.coefficients[0]}), calculus to do")
+
+    new_coefs = {**right.coefficients}
     #! Need to be add at the end to be printed at the beginning
     new_coefs[0] = left
     return MOpolynomial(right.variable, new_coefs)
@@ -145,13 +148,16 @@ def mopolynomial_moscalar(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^2 + 2x + 1 / 5>
     """
+    if 0 in left.coefficients.keys():
+        raise NotImplementedError("Polynomial with constant, calculus to do")
+
     #! Need to be add at the beginning to be printed at the end
     new_coefs = {0: right}
     new_coefs = {**new_coefs, **left.coefficients}
     return MOpolynomial(left.variable, new_coefs)
 
 @add.register(MOstr, MOstrPower)
-def moscalar_mostr(left, right):
+def mostr_mostrpower(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
     >>> a = MOstr('x')
@@ -167,7 +173,7 @@ def moscalar_mostr(left, right):
     return MOpolynomial(left , {1: 1, right.power: 1})
 
 @add.register(MOstrPower, MOstr)
-def moscalar_mostr(left, right):
+def mostrpower_mostr(left, right):
     """ add a scalar with a letter to create a MOpolynomial
 
     >>> a = MOstrPower('x', 3)
@@ -191,7 +197,10 @@ def mostr_mopolynomial(left, right):
     >>> add(a, b)
     <MOpolynomial x + 3x^2 + 1>
     """
-    new_coefs = right.coefficients
+    if 1 in right.coefficients.keys():
+        raise NotImplementedError("Polynomial with no constant, calculus to do")
+
+    new_coefs = {**right.coefficients}
     #! Need to be add at the end to be printed at the beginning
     new_coefs[1] = 1
     return MOpolynomial(right.variable, new_coefs)
@@ -205,6 +214,9 @@ def mopolynomial_mostr(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^2 + 1 + x>
     """
+    if 1 in left.coefficients.keys():
+        raise NotImplementedError("Polynomial with no constant, calculus to do")
+
     new_coefs = {1: 1}
     new_coefs = {**new_coefs, **left.coefficients}
     return MOpolynomial(left.variable, new_coefs)
@@ -218,7 +230,10 @@ def mostrpower_mopolynomial(left, right):
     >>> add(a, b)
     <MOpolynomial x^2 + 4x^3 + 2x + 1>
     """
-    new_coefs = right.coefficients
+    if left.power in right.coefficients.keys():
+        raise NotImplementedError("Degree in common, need to compute")
+
+    new_coefs = {**right.coefficients}
     #! Need to be add at the end to be printed at the beginning
     new_coefs[left.power] = 1
     return MOpolynomial(right.variable, new_coefs)
@@ -232,6 +247,9 @@ def mopolynomial_mostrpower(left, right):
     >>> add(a, b)
     <MOpolynomial 4x^3 + 2x + 1 + x^2>
     """
+    if right.power in left.coefficients.keys():
+        raise NotImplementedError("Degree in common, need to compute")
+
     new_coefs = {right.power: 1}
     new_coefs = {**new_coefs, **left.coefficients}
     return MOpolynomial(left.variable, new_coefs)
@@ -245,7 +263,10 @@ def momonomial_mopolynomial(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^2 + 4x^3 + 2x + 1>
     """
-    new_coefs = right.coefficients
+    if left.power in right.coefficients.keys():
+        raise NotImplementedError("Degree in common, need to compute")
+
+    new_coefs = {**right.coefficients}
     #! Need to be add at the end to be printed at the beginning
     new_coefs[left.power] = left.coefficient
     return MOpolynomial(right.variable, new_coefs)
@@ -259,6 +280,9 @@ def mopolynomial_momonomial(left, right):
     >>> add(a, b)
     <MOpolynomial 4x^3 + 2x + 1 + 3x^2>
     """
+    if right.power in left.coefficients.keys():
+        raise NotImplementedError("Degree in common, need to compute")
+
     new_coefs = {right.power: right.coefficient}
     new_coefs = {**new_coefs, **left.coefficients}
     return MOpolynomial(left.variable, new_coefs)
@@ -274,6 +298,10 @@ def mopolynomial_mopolynomial(left, right):
     >>> add(b, a)
     <MOpolynomial 4x^3 + 2x + 3x^2 + 1>
     """
+    common_degree = set(left.monomials.keys()).intersection(right.monomials.keys()) 
+    if common_degree:
+        raise NotImplementedError("Degree in common, need to compute")
+
     new_coefs = {**right.coefficients, **left.coefficients}
     return MOpolynomial(right.variable, new_coefs)
 
@@ -286,6 +314,9 @@ def mostr_monomial(left, right):
     >>> add(a, b)
     <MOpolynomial x + 3x^4>
     """
+    if right.power == 1:
+        raise NotImplementedError("Monomial is deg 1, need to compute")
+
     return MOpolynomial(right.variable, 
                         {right.power: right.coefficient, 1: 1}
                         )
@@ -299,6 +330,9 @@ def monomial_mostr(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^4 + x>
     """
+    if left.power == 1:
+        raise NotImplementedError("Monomial is deg 1, need to compute")
+
     return MOpolynomial(left.variable, 
                         {1: 1, left.power: left.coefficient}
                         )
@@ -312,6 +346,9 @@ def mostrpower_monomial(left, right):
     >>> add(a, b)
     <MOpolynomial x^2 + 3x^4>
     """
+    if left.power == right.power:
+        raise NotImplementedError("MostrPower and MOMonomial are same degree, need to compute")
+
     return MOpolynomial(right.variable, 
                         {right.power: right.coefficient, left.power: 1}
                         )
@@ -325,6 +362,9 @@ def monomial_mostrpower(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^4 + x^3>
     """
+    if left.power == right.power:
+        raise NotImplementedError("MostrPower and MOMonomial are same degree, need to compute")
+
     return MOpolynomial(left.variable, 
                         {right.power: 1, left.power: left.coefficient}
                         )
@@ -338,6 +378,9 @@ def monomial_momonomial(left, right):
     >>> add(a, b)
     <MOpolynomial 3x^4 + 2x^3>
     """
+    if left.power == right.power:
+        raise NotImplementedError("MOMonomials are same degree, need to compute")
+
     return MOpolynomial(left.variable, 
                         {right.power: right.coefficient, left.power: left.coefficient}
                         )