diff --git a/poincare/Makefile b/poincare/Makefile
index 8bee4c7ef..d9750e607 100644
--- a/poincare/Makefile
+++ b/poincare/Makefile
@@ -23,6 +23,7 @@ objs += $(addprefix poincare/src/,\
   logarithm.o\
   matrix.o\
   matrix_data.o\
+  n_context.o\
   nth_root.o\
   opposite.o\
   parenthesis.o\
@@ -30,6 +31,7 @@ objs += $(addprefix poincare/src/,\
   product.o\
   sine.o\
   subtraction.o\
+  sum.o\
   symbol.o\
   tangent.o\
   x_context.o\
diff --git a/poincare/include/poincare.h b/poincare/include/poincare.h
index 9d74b0107..f22d001c6 100644
--- a/poincare/include/poincare.h
+++ b/poincare/include/poincare.h
@@ -18,6 +18,7 @@
 #include <poincare/logarithm.h>
 #include <poincare/matrix.h>
 #include <poincare/matrix_data.h>
+#include <poincare/n_context.h>
 #include <poincare/nth_root.h>
 #include <poincare/opposite.h>
 #include <poincare/parenthesis.h>
@@ -25,6 +26,7 @@
 #include <poincare/product.h>
 #include <poincare/sine.h>
 #include <poincare/subtraction.h>
+#include <poincare/sum.h>
 #include <poincare/symbol.h>
 #include <poincare/tangent.h>
 #include <poincare/x_context.h>
diff --git a/poincare/include/poincare/expression.h b/poincare/include/poincare/expression.h
index 76a4878cd..97baff133 100644
--- a/poincare/include/poincare/expression.h
+++ b/poincare/include/poincare/expression.h
@@ -26,6 +26,7 @@ class Expression {
       Power,
       Product,
       Sine,
+      Sum,
       Subtraction,
       Symbol,
       Tangent,
diff --git a/poincare/include/poincare/n_context.h b/poincare/include/poincare/n_context.h
new file mode 100644
index 000000000..d569c4ce1
--- /dev/null
+++ b/poincare/include/poincare/n_context.h
@@ -0,0 +1,17 @@
+#ifndef POINCARE_N_CONTEXT_H
+#define POINCARE_N_CONTEXT_H
+
+#include <poincare/context.h>
+#include <poincare/float.h>
+
+class NContext : public Context {
+public:
+  NContext(Context * parentContext = nullptr);
+  void setExpressionForSymbolName(Expression * expression, const Symbol * symbol) override;
+  const Expression * expressionForSymbol(const Symbol * symbol) override;
+private:
+  Float m_nValue;
+  Context * m_parentContext;
+};
+
+#endif
\ No newline at end of file
diff --git a/poincare/include/poincare/sum.h b/poincare/include/poincare/sum.h
new file mode 100644
index 000000000..f9afbcc0e
--- /dev/null
+++ b/poincare/include/poincare/sum.h
@@ -0,0 +1,16 @@
+#ifndef POINCARE_SUM_H
+#define POINCARE_SUM_H
+
+#include <poincare/function.h>
+#include <poincare/n_context.h>
+
+class Sum : public Function {
+public:
+  Sum();
+  float approximate(Context & context) const override;
+  Type type() const override;
+  Expression * cloneWithDifferentOperands(Expression ** newOperands,
+      int numberOfOperands, bool cloneOperands = true) const override;
+};
+
+#endif
diff --git a/poincare/include/poincare/x_context.h b/poincare/include/poincare/x_context.h
index bee9ac94b..0755bf68e 100644
--- a/poincare/include/poincare/x_context.h
+++ b/poincare/include/poincare/x_context.h
@@ -1,5 +1,5 @@
-#ifndef POINCARE_LOCAL_CONTEXT_H
-#define POINCARE_LOCAL_CONTEXT_H
+#ifndef POINCARE_X_CONTEXT_H
+#define POINCARE_X_CONTEXT_H
 
 #include <poincare/context.h>
 #include <poincare/float.h>
diff --git a/poincare/src/expression_lexer.l b/poincare/src/expression_lexer.l
index b98123782..a31ed323c 100644
--- a/poincare/src/expression_lexer.l
+++ b/poincare/src/expression_lexer.l
@@ -89,6 +89,7 @@ int { poincare_expression_yylval.expression = new Integral(); return FUNCTION; }
 tan { poincare_expression_yylval.expression = new Tangent(); return FUNCTION; }
 log { poincare_expression_yylval.expression = new Logarithm(); return FUNCTION; }
 root { poincare_expression_yylval.expression = new NthRoot(); return FUNCTION; }
+sum { poincare_expression_yylval.expression = new Sum(); return FUNCTION; }
 \+ { return PLUS; }
 \- { return MINUS; }
 \* { return MULTIPLY; }
diff --git a/poincare/src/n_context.cpp b/poincare/src/n_context.cpp
new file mode 100644
index 000000000..985a60489
--- /dev/null
+++ b/poincare/src/n_context.cpp
@@ -0,0 +1,24 @@
+#include <poincare/n_context.h>
+
+NContext::NContext(::Context * parentContext) :
+  m_nValue(Float(0.0f)),
+  m_parentContext(parentContext)
+{
+}
+
+void NContext::setExpressionForSymbolName(Expression * expression, const Symbol * symbol) {
+  if (symbol->name() == 'n') {
+  	m_nValue = Float((int)expression->approximate(*m_parentContext));
+  } else {
+    m_parentContext->setExpressionForSymbolName(expression, symbol);
+  }
+}
+
+const Expression * NContext::expressionForSymbol(const Symbol * symbol) {
+  if (symbol->name() == 'n') {
+    return &m_nValue;
+  } else {
+    return m_parentContext->expressionForSymbol(symbol);
+  }
+}
+
diff --git a/poincare/src/sum.cpp b/poincare/src/sum.cpp
new file mode 100644
index 000000000..e5a2785d7
--- /dev/null
+++ b/poincare/src/sum.cpp
@@ -0,0 +1,39 @@
+#include <poincare/sum.h>
+#include <poincare/symbol.h>
+#include <poincare/float.h>
+
+extern "C" {
+#include <assert.h>
+}
+
+Sum::Sum() :
+  Function("sum")
+{
+}
+
+Expression::Type Sum::type() const {
+  return Type::Sum;
+}
+
+Expression * Sum::cloneWithDifferentOperands(Expression** newOperands,
+        int numberOfOperands, bool cloneOperands) const {
+  assert(numberOfOperands == 2);
+  assert(newOperands != nullptr);
+  Sum * s = new Sum();
+  s->setArgument(newOperands, numberOfOperands, cloneOperands);
+  return s;
+}
+
+float Sum::approximate(Context& context) const {
+  NContext nContext = NContext(&context);
+  Symbol nSymbol = Symbol('n');
+  int start = m_args[1]->approximate(context);
+  int end = m_args[2]->approximate(context);
+  float result = 0.0f;
+  for (int i = start; i <= end; i++) {
+    Float iExpression = Float(i);
+    nContext.setExpressionForSymbolName(&iExpression, &nSymbol);
+    result += m_args[0]->approximate(nContext);
+  }
+  return result;
+}