diff --git a/quantities/decorators.py b/quantities/decorators.py
@@ -42,11 +42,11 @@ def __call__(self, new_method):
        header = self.header

        if original_doc and new_doc:
-            new_method.__doc__ = """
-    {}
-    {}
-    {}
-        """.format(original_doc, header, new_doc)

        elif original_doc:
            new_method.__doc__ = original_doc

diff --git a/quantities/markup.py b/quantities/markup.py
@@ -61,12 +61,12 @@ def format_units(udict):
            u = key.symbol
        if d>0:
            if d != 1:
-                u = u + ('**%s'%d).rstrip('0').rstrip('.')
            num.append(u)
        elif d<0:
            d = -d
            if d != 1:
-                u = u + ('**%s'%d).rstrip('0').rstrip('.')
            den.append(u)
    res = '*'.join(num)
    if len(den):
@@ -156,6 +156,6 @@ def format_units_html(udict,font='%s',mult=r'&sdot;',paren=False):
    # Remove multiplication signs
    res = re.sub(r'\*',mult,res)
    if paren and not compound:
-        res = '(%s)' % res
    res = font % res
    return res
diff --git a/quantities/quantity.py b/quantities/quantity.py
@@ -22,8 +22,7 @@ def validate_unit_quantity(value):
        assert value.magnitude == 1
    except AssertionError:
        raise ValueError(
-                'units must be a scalar Quantity with unit magnitude, got %s'\
-                %value
            )
    return value

@@ -40,8 +39,7 @@ def validate_dimensionality(value):
        return value.copy()
    else:
        raise TypeError(
-            'units must be a quantity, string, or dimensionality, got %s'\
-            %type(value)
        )

def get_conversion_factor(from_u, to_u):
@@ -187,8 +185,7 @@ def units(self, units):
            cf = get_conversion_factor(from_u, to_u)
        except AssertionError:
            raise ValueError(
-                'Unable to convert between units of "%s" and "%s"'
-                %(from_u._dimensionality, to_u._dimensionality)
            )
        mag = self.magnitude
        mag *= cf
@@ -204,7 +201,7 @@ def rescale(self, units=None, dtype=None):
            try:
                return self.rescale_preferred()
            except Exception as e:
-                raise Exception('No argument passed to `.rescale` and %s' % e)
        to_dims = validate_dimensionality(units)
        if dtype is None:
            dtype = self.dtype
@@ -216,8 +213,7 @@ def rescale(self, units=None, dtype=None):
            cf = get_conversion_factor(from_u, to_u)
        except AssertionError:
            raise ValueError(
-                'Unable to convert between units of "%s" and "%s"'
-                %(from_u._dimensionality, to_u._dimensionality)
            )
        new_magnitude = cf*self.magnitude
        dtype = np.result_type(dtype, new_magnitude)
@@ -277,9 +273,9 @@ def __array_prepare__(self, obj, context=None):
            res._dimensionality = p_dict[uf](*objs)
        except KeyError:
            raise ValueError(
-                """ufunc %r not supported by quantities
                please file a bug report at https://github.com/python-quantities
-                """ % uf
                )
        return res

@@ -367,17 +363,15 @@ def __round__(self, decimals=0):

    @with_doc(np.ndarray.__repr__)
    def __repr__(self):
-        return '%s * %s'%(
-            repr(self.magnitude), self.dimensionality.string
-        )

    @with_doc(np.ndarray.__str__)
    def __str__(self):
        if markup.config.use_unicode:
            dims = self.dimensionality.unicode
        else:
            dims = self.dimensionality.string
-        return '%s %s'%(str(self.magnitude), dims)

    if tuple(map(int, np.__version__.split('.')[:2])) >= (1, 14):
        # in numpy 1.14 the formatting of scalar values was changed

diff --git a/quantities/registry.py b/quantities/registry.py
@@ -21,7 +21,7 @@ def __getitem__(self, string):
            except NameError:
                # could return self['UnitQuantity'](string)
                raise LookupError(
-                    'Unable to parse units: "%s"'%string
                )

        def __setitem__(self, string, val):
@@ -32,8 +32,7 @@ def __setitem__(self, string, val):
                if val == self.__context[string]:
                    return
                raise KeyError(
-                    '%s has already been registered for %s'
-                    % (string, self.__context[string])
                )
            self.__context[string] = val


diff --git a/quantities/tests/common.py b/quantities/tests/common.py
@@ -20,7 +20,7 @@ def assertQuantityEqual(self, q1, q2, msg=None, delta=None):
        precision.
        """
        delta = 1e-5 if delta is None else delta
-        msg = '' if msg is None else ' (%s)' % msg

        q1 = Quantity(q1)
        q2 = Quantity(q2)
@@ -30,8 +30,7 @@ def assertQuantityEqual(self, q1, q2, msg=None, delta=None):
                )
        if not np.all(np.abs(q1.magnitude - q2.magnitude) < delta):
            raise self.failureException(
-                "Magnitudes differ by more than %g (%s vs %s)%s"
-                % (delta, q1.magnitude, q2.magnitude, msg)
                )

        d1 = getattr(q1, '_dimensionality', None)

diff --git a/quantities/tests/test_units.py b/quantities/tests/test_units.py
@@ -17,7 +17,7 @@ def setunits(u, v):
            u.units = v

        def inplace(op, u, val):
-            getattr(u, '__i%s__'%op)(val)

        self.assertRaises(AttributeError, setunits, pq.m, pq.ft)
        self.assertRaises(TypeError, inplace, 'add', pq.m, pq.m)

diff --git a/quantities/umath.py b/quantities/umath.py
@@ -344,8 +344,7 @@ def arctan2(x1, x2, out=None):

    if x1._dimensionality.simplified != x2._dimensionality.simplified:
        raise ValueError(
-            'x1 and x2 must have identical units, got "%s" and "%s"'\
-            % (str(x1._dimensionality), str(x2._dimensionality))
        )

    return Quantity(
@@ -369,8 +368,7 @@ def hypot(x1, x2, out = None):

    if x1._dimensionality != x2._dimensionality:
        raise ValueError(
-            'x1 and x2 must have identical units, got "%s" and "%s"'\
-            % (str(x1._dimensionality), str(x2._dimensionality))
        )

    return Quantity(

diff --git a/quantities/uncertainquantity.py b/quantities/uncertainquantity.py
@@ -184,11 +184,7 @@ def __str__(self):
            dims = self.dimensionality.unicode
        else:
            dims = self.dimensionality.string
-        s = '%s %s\n+/-%s (1 sigma)'%(
-            str(self.magnitude),
-            dims,
-            str(self.uncertainty)
-        )
        if markup.config.use_unicode:
            return s.replace('+/-', '±').replace(' sigma', 'σ')
        return s

diff --git a/quantities/unitquantity.py b/quantities/unitquantity.py
@@ -35,13 +35,12 @@ def __new__(
        try:
            assert isinstance(name, str)
        except AssertionError:
-            raise TypeError('name must be a string, got %s (not unicode)'%name)
        try:
            assert symbol is None or isinstance(symbol, str)
        except AssertionError:
            raise TypeError(
-                'symbol must be a string, '
-                'got %s (u_symbol can be unicode)'%symbol
            )

        ret = numpy.array(1, dtype='d').view(cls)
@@ -139,29 +138,27 @@ def units(self, units):
    def __repr__(self):
        ref = self._definition
        if ref:
-            ref = ', %s * %s'%(str(ref.magnitude), ref.dimensionality.string)
        else:
            ref = ''
        symbol = self._symbol
-        symbol = ', %s'%(repr(symbol)) if symbol else ''
        if markup.config.use_unicode:
            u_symbol = self._u_symbol
-            u_symbol = ', %s'%(repr(u_symbol)) if u_symbol else ''
        else:
            u_symbol = ''
-        return '%s(%s%s%s%s)'%(
-            self.__class__.__name__, repr(self.name), ref, symbol, u_symbol
-        )

    @with_doc(Quantity.__str__, use_header=False)
    def __str__(self):
        if self.u_symbol != self.name:
            if markup.config.use_unicode:
-                s = '1 %s (%s)'%(self.u_symbol, self.name)
            else:
-                s = '1 %s (%s)'%(self.symbol, self.name)
        else:
-            s = '1 %s'%self.name

        return s

@@ -381,14 +378,14 @@ def __init__(self, name):

    @with_doc(UnitQuantity.__add__, use_header=False)
    def __repr__(self):
-        return '1 %s'%self.name

    @property
    def name(self):
        if markup.config.use_unicode:
-            return '(%s)'%(markup.superscript(self._name))
        else:
-            return '(%s)'%self._name

    def __reduce__(self):
        """
@@ -476,7 +473,7 @@ def set_default_units(
        try:
            assert system in ('si', 'cgs')
        except AssertionError:
-            raise ValueError('system must be "SI" or "cgs", got "%s"' % system)
        if system == 'si':
            UnitCurrent.set_default_unit('A')
            UnitLength.set_default_unit('m')