diff --git a/pymath/calculus/abstract_polynom.py b/pymath/calculus/abstract_polynom.py
index eb6fa95..06a3b0f 100644
--- a/pymath/calculus/abstract_polynom.py
+++ b/pymath/calculus/abstract_polynom.py
@@ -367,7 +367,7 @@ class AbstractPolynom(Explicable):
             steps.append(AbstractPolynom(coefs, self._letter))
 
         ans, steps = steps[-1], steps[:-1]
-        ans.steps = steps
+        ans.this_append_before(steps)
 
         return ans
 
@@ -407,7 +407,7 @@ class AbstractPolynom(Explicable):
         ini_step = [Expression(self.postfix_tokens +
                                o_poly.postfix_tokens + [op.add])]
         ans = p.simplify()
-        ans.steps = ini_step + ans.steps
+        ans.this_append_before(ini_step)
         return ans
 
     def __radd__(self, other):
@@ -427,7 +427,7 @@ class AbstractPolynom(Explicable):
         ini_step = [Expression(self.postfix_tokens + [op.sub1])]
         ans = AbstractPolynom([-i for i in self._coef],
                               letter=self._letter).simplify()
-        ans.steps = ini_step + ans.steps
+        ans.this_append_before(ini_step)
         return ans
 
     def __sub__(self, other):
@@ -452,10 +452,9 @@ class AbstractPolynom(Explicable):
         ini_step = [Expression(self.postfix_tokens +
                                o_poly.postfix_tokens + [op.sub])]
         o_poly = -o_poly
-        #ini_step += o_poly.steps
 
         ans = self + o_poly
-        ans.steps = ini_step + ans.steps
+        ans.this_append_before(ini_step)
 
         return ans
 
@@ -465,27 +464,32 @@ class AbstractPolynom(Explicable):
         return o_poly.__sub__(self)
 
     def __mul__(self, other):
-        """ Overload *
+        r""" Overload *
 
         >>> p = AbstractPolynom([1,2])
         >>> p*3
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [3, 6]>
+        >>> for i in (p*3).explain():
+        ...    print(i)
+        ( 2 x + 1 ) \times 3
+        2 \times 3 x + 3
+        6 x + 3
         >>> (p*3).steps
-        [[< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 3, *] >], < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [3, < <class 'pymath.calculus.expression.Expression'> [2, 3, *] >]>]
+        [< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 3, *] >, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [3, < <class 'pymath.calculus.expression.Expression'> [2, 3, *] >]>]
         >>> q = AbstractPolynom([0,0,4])
         >>> q*3
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, 12]>
         >>> (q*3).steps
-        [[< <class 'pymath.calculus.expression.Expression'> [4, 'x', 2, ^, *, 3, *] >], < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, < <class 'pymath.calculus.expression.Expression'> [4, 3, *] >]>]
+        [< <class 'pymath.calculus.expression.Expression'> [4, 'x', 2, ^, *, 3, *] >, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, < <class 'pymath.calculus.expression.Expression'> [4, 3, *] >]>]
         >>> r = AbstractPolynom([0,1])
         >>> r*3
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 3]>
         >>> (r*3).steps
-        [[< <class 'pymath.calculus.expression.Expression'> ['x', 3, *] >]]
+        [< <class 'pymath.calculus.expression.Expression'> ['x', 3, *] >]
         >>> p*q
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, 4, 8]>
         >>> (p*q).steps
-        [[< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 4, 'x', 2, ^, *, *] >], < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, 4, < <class 'pymath.calculus.expression.Expression'> [2, 4, *] >]>]
+        [< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 4, 'x', 2, ^, *, *] >, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, 4, < <class 'pymath.calculus.expression.Expression'> [2, 4, *] >]>]
         >>> p*r
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 1, 2]>
         >>> P = AbstractPolynom([1,2,3])
@@ -520,7 +524,7 @@ class AbstractPolynom(Explicable):
                                o_poly.postfix_tokens + [op.mul])]
         ans = p.simplify()
 
-        ans.steps = [ini_step] + ans.steps
+        ans.this_append_before(ini_step)
         return ans
 
     def __rmul__(self, other):
@@ -541,7 +545,7 @@ class AbstractPolynom(Explicable):
         >>> p**2
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [1, 4, 4]>
         >>> (p**2).steps
-        [< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 2, ^] >, [< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 2, 'x', *, 1, +, *] >], < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [1, [2, 2], < <class 'pymath.calculus.expression.Expression'> [2, 2, *] >]>, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [1, < <class 'pymath.calculus.expression.Expression'> [2, 2, +] >, 4]>]
+        [< <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 2, ^] >, < <class 'pymath.calculus.expression.Expression'> [2, 'x', *, 1, +, 2, 'x', *, 1, +, *] >, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [1, [2, 2], < <class 'pymath.calculus.expression.Expression'> [2, 2, *] >]>, < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [1, < <class 'pymath.calculus.expression.Expression'> [2, 2, +] >, 4]>]
         >>> p = AbstractPolynom([0,0,1])
         >>> p**3
         < <class 'pymath.calculus.abstract_polynom.AbstractPolynom'> [0, 0, 0, 0, 0, 0, 1]>
@@ -576,7 +580,7 @@ class AbstractPolynom(Explicable):
                 raise AttributeError(
                     "__pw__ not implemented yet when power is greatter than 2")
 
-        ans.steps = ini_step + ans.steps
+        ans.this_append_before(ini_step)
         return ans
 
     def __xor__(self, power):
diff --git a/pymath/calculus/explicable.py b/pymath/calculus/explicable.py
index b131be8..11bffb5 100644
--- a/pymath/calculus/explicable.py
+++ b/pymath/calculus/explicable.py
@@ -61,6 +61,23 @@ class Explicable(Renderable):
             else:
                 return False
 
+    def this_append_before(self, steps):
+        """ Add steps at the beginning of self.steps
+
+        :param steps: list of steps that append before
+
+        >>> e = Explicable()
+        >>> s = ['eat', 'sleep']
+        >>> e.this_append_before(s)
+        >>> print(e.steps)
+        ['eat', 'sleep']
+        >>> s0 = ['cook']
+        >>> e.this_append_before(s0)
+        >>> print(e.steps)
+        ['cook', 'eat', 'sleep']
+        """
+        self.steps = steps + self.steps
+
 class Explicable_int(int, Explicable):
     """ An Explicable_int is an int which can be explain """
     isNumber = True