diff --git a/mapytex/calculus/core/MO/monomial.py b/mapytex/calculus/core/MO/monomial.py
index ede5a68..0ecc764 100644
--- a/mapytex/calculus/core/MO/monomial.py
+++ b/mapytex/calculus/core/MO/monomial.py
@@ -114,15 +114,21 @@ class MOMonomial(MO):
         self._power = _power
 
         if self._power == 1:
-            _tree = Tree("*",
-                        self._coefficient,
-                        self._variable
-                        )
+            if self._coefficient == 1:
+                _tree = self._variable
+            else:
+                _tree = Tree("*",
+                             self._coefficient,
+                             self._variable
+                             )
         else:
-            _tree = Tree("*",
-                        self._coefficient,
-                        MOstrPower(self._variable, self._power)
-                        )
+            if self._coefficient == 1:
+                _tree = MOstrPower(self._variable, self._power)
+            else:
+                _tree = Tree("*",
+                             self._coefficient,
+                             MOstrPower(self._variable, self._power)
+                             )
 
         MO.__init__(self, _tree)
 
diff --git a/mapytex/calculus/core/MO/polynomial.py b/mapytex/calculus/core/MO/polynomial.py
index ad9c3c6..602e7f7 100644
--- a/mapytex/calculus/core/MO/polynomial.py
+++ b/mapytex/calculus/core/MO/polynomial.py
@@ -33,6 +33,8 @@ class MOpolynomial(MO):
         <MOpolynomial 3x^2 + 2x + 1>
         >>> MOpolynomial('x', {0: 1, 3: 4})
         <MOpolynomial 4x^3 + 1>
+        >>> MOpolynomial('x', {0: 1, 3: 1})
+        <MOpolynomial x^3 + 1>
 
 
         """
diff --git a/mapytex/calculus/core/typing/__init__.py b/mapytex/calculus/core/typing/__init__.py
index 648c543..7c56f73 100644
--- a/mapytex/calculus/core/typing/__init__.py
+++ b/mapytex/calculus/core/typing/__init__.py
@@ -11,7 +11,7 @@ Computing with MO
 """
 
 from .exceptions import TypingError
-# from .add import add
+from .add import add
 # from .minus import minus
 # from .multiply import multiply
 from .divide import divide
@@ -27,7 +27,7 @@ from tabulate import tabulate
 MOS = [ MOnumber, MOstr, MOFraction, MOstrPower, MOMonomial ]
 
 OPERATIONS = {
-        # "+": add, 
+        "+": add, 
         # "-": minus, 
         # "*": multiply,
         "/": divide,