diff --git a/runners/calculator/calculatorrunner.h b/runners/calculator/calculatorrunner.h
--- a/runners/calculator/calculatorrunner.h
+++ b/runners/calculator/calculatorrunner.h
@@ -47,7 +47,7 @@
         QMimeData * mimeDataForMatch(const Plasma::QueryMatch &match) override;
 
     private:
-        QString calculate(const QString& term);
+        QString calculate(const QString& term, bool *isApproximate);
         void userFriendlySubstitutions(QString& cmd);
         void powSubstitutions(QString& cmd);
         void hexSubstitutions(QString& cmd);
diff --git a/runners/calculator/calculatorrunner.cpp b/runners/calculator/calculatorrunner.cpp
--- a/runners/calculator/calculatorrunner.cpp
+++ b/runners/calculator/calculatorrunner.cpp
@@ -262,7 +262,8 @@
     cmd.replace(QRegExp(QStringLiteral("([a-zA-Z]+)")), QStringLiteral("Math.\\1")); //needed for accessing math funktions like sin(),....
     #endif
 
-    QString result = calculate(cmd);
+    bool isApproximate = false;
+    QString result = calculate(cmd, &isApproximate);
     if (!result.isEmpty() && result != cmd) {
         if (toHex) {
             result = "0x" + QString::number(result.toInt(), 16).toUpper();
@@ -272,19 +273,22 @@
         match.setType(Plasma::QueryMatch::InformationalMatch);
         match.setIconName(QStringLiteral("accessories-calculator"));
         match.setText(result);
+        if (isApproximate) {
+            match.setSubtext(i18nc("The result of the calculation is only an approximation", "Approximation"));
+        }
         match.setData(result);
         match.setId(term);
         context.addMatch(match);
     }
 }
 
-QString CalculatorRunner::calculate(const QString& term)
+QString CalculatorRunner::calculate(const QString& term, bool *isApproximate)
 {
     #ifdef ENABLE_QALCULATE
     QString result;
 
     try {
-        result = m_engine->evaluate(term);
+        result = m_engine->evaluate(term, isApproximate);
     } catch(std::exception& e) {
         qDebug() << "qalculate error: " << e.what();
     }
diff --git a/runners/calculator/qalculate_engine.h b/runners/calculator/qalculate_engine.h
--- a/runners/calculator/qalculate_engine.h
+++ b/runners/calculator/qalculate_engine.h
@@ -35,7 +35,7 @@
 	QString lastResult() const { return m_lastResult; }
 
 public Q_SLOTS:
-	QString evaluate(const QString& expression);
+    QString evaluate(const QString& expression, bool *isApproximate = nullptr);
 	void updateExchangeRates();
 
 	void copyToClipboard(bool flag = true);
diff --git a/runners/calculator/qalculate_engine.cpp b/runners/calculator/qalculate_engine.cpp
--- a/runners/calculator/qalculate_engine.cpp
+++ b/runners/calculator/qalculate_engine.cpp
@@ -79,7 +79,7 @@
     }
 }
 
-QString QalculateEngine::evaluate(const QString& expression)
+QString QalculateEngine::evaluate(const QString& expression, bool *isApproximate)
 {
     if (expression.isEmpty()) {
         return "";
@@ -98,6 +98,10 @@
     eo.parse_options.angle_unit = ANGLE_UNIT_RADIANS;
     eo.structuring = STRUCTURING_SIMPLIFY;
 
+    // suggested in https://github.com/Qalculate/libqalculate/issues/16
+    // to avoid memory overflow for seemingly innocent calculations (Bug 277011)
+    eo.approximation = APPROXIMATION_APPROXIMATE;
+
     CALCULATOR->setPrecision(16);
     MathStructure result = CALCULATOR->calculate(ctext, eo);
 
@@ -114,6 +118,10 @@
 
     m_lastResult = result.print(po).c_str();
 
+    if (isApproximate) {
+        *isApproximate = result.isApproximate();
+    }
+
     return m_lastResult;
 }