diff --git a/apps/calculation/calculation.cpp b/apps/calculation/calculation.cpp
index 93eab7d9a..182b769d3 100644
--- a/apps/calculation/calculation.cpp
+++ b/apps/calculation/calculation.cpp
@@ -31,6 +31,15 @@ Calculation::~Calculation() {
   }
 }
 
+Calculation& Calculation::operator=(const Calculation& other) {
+  const char * otherInputText = other.m_inputText;
+  const char * otherOutputText = other.m_outputText;
+  reset();
+  strlcpy(m_inputText, otherInputText, sizeof(m_inputText));
+  strlcpy(m_outputText, otherOutputText, sizeof(m_outputText));
+  return *this;
+}
+
 void Calculation::reset() {
   m_inputText[0] = 0;
   m_outputText[0] = 0;
diff --git a/apps/calculation/calculation.h b/apps/calculation/calculation.h
index 571e2300b..c9b52fa38 100644
--- a/apps/calculation/calculation.h
+++ b/apps/calculation/calculation.h
@@ -10,9 +10,9 @@ class Calculation {
 public:
   Calculation();
   ~Calculation(); // Delete expression and layout, if needed
+  Calculation& operator=(const Calculation& other);
   Calculation(const Calculation& other) = delete;
   Calculation(Calculation&& other) = delete;
-  Calculation& operator=(const Calculation& other) = delete;
   Calculation& operator=(Calculation&& other) = delete;
   /* c.reset() is the equivalent of c = Calculation() without copy assingment. */
   void reset();
diff --git a/apps/calculation/calculation_store.cpp b/apps/calculation/calculation_store.cpp
index 34ab18c89..6c8e3fa9d 100644
--- a/apps/calculation/calculation_store.cpp
+++ b/apps/calculation/calculation_store.cpp
@@ -5,23 +5,23 @@ using namespace Poincare;
 namespace Calculation {
 
 CalculationStore::CalculationStore() :
-  m_start(m_calculations)
+  m_startIndex(0)
 {
 }
 
 Calculation * CalculationStore::push(const char * text, Context * context) {
-  Calculation * result = m_start;
-  m_start->setContent(text, context);
-  m_start++;
-  if (m_start >= m_calculations + k_maxNumberOfCalculations) {
-    m_start = m_calculations;
+  Calculation * result = &m_calculations[m_startIndex];
+  result->setContent(text, context);
+  m_startIndex++;
+  if (m_startIndex >= k_maxNumberOfCalculations) {
+    m_startIndex = 0;
   }
   return result;
 }
 
 Calculation * CalculationStore::calculationAtIndex(int i) {
   int j = 0;
-  Calculation * currentCalc = m_start;
+  Calculation * currentCalc = &m_calculations[m_startIndex];
   Calculation * previousCalc = nullptr;
   while (j <= i) {
     if (!currentCalc++->isEmpty()) {
@@ -47,17 +47,39 @@ int CalculationStore::numberOfCalculations() {
 }
 
 void CalculationStore::deleteCalculationAtIndex(int i) {
-  calculationAtIndex(i)->reset();
+  int numberOfCalc = numberOfCalculations();
+  assert(i >= 0 && i < numberOfCalc);
+  int indexFirstCalc = m_startIndex;
+  while (m_calculations[indexFirstCalc].isEmpty()) {
+    indexFirstCalc++;
+    if (indexFirstCalc == k_maxNumberOfCalculations) {
+      indexFirstCalc = 0;
+    }
+    assert(indexFirstCalc != m_startIndex);
+  }
+  int absoluteIndexCalculationI = indexFirstCalc+i;
+  absoluteIndexCalculationI = absoluteIndexCalculationI >= k_maxNumberOfCalculations ? absoluteIndexCalculationI - k_maxNumberOfCalculations : absoluteIndexCalculationI;
+
+  int index = absoluteIndexCalculationI;
+  for (int k = i; k < numberOfCalc-1; k++) {
+    int nextIndex = index+1 >= k_maxNumberOfCalculations ? 0 : index+1;
+    m_calculations[index] = m_calculations[nextIndex];
+    index++;
+    if (index == k_maxNumberOfCalculations) {
+      index = 0;
+    }
+  }
+  m_calculations[index].reset();
+  m_startIndex--;
+  if (m_startIndex == -1) {
+    m_startIndex = k_maxNumberOfCalculations-1;
+  }
 }
 
 void CalculationStore::deleteAll() {
-  m_start = m_calculations;
-  Calculation * currentCalc= m_start;
-  while (currentCalc < m_calculations + k_maxNumberOfCalculations) {
-    if (!currentCalc->isEmpty()) {
-      currentCalc->reset();
-    }
-    currentCalc++;
+  m_startIndex = 0;
+  for (int i = 0; i < k_maxNumberOfCalculations; i++) {
+    m_calculations[i].reset();
   }
 }
 
diff --git a/apps/calculation/calculation_store.h b/apps/calculation/calculation_store.h
index 0348c1844..15eeb0b72 100644
--- a/apps/calculation/calculation_store.h
+++ b/apps/calculation/calculation_store.h
@@ -18,7 +18,7 @@ public:
   void tidy();
 private:
   static constexpr int k_maxNumberOfCalculations = 10;
-  Calculation * m_start;
+  int m_startIndex;
   Calculation m_calculations[k_maxNumberOfCalculations];
 };