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Lesson 27 — Ultimate: RPN calculator
Boss level: evaluate expressions
Use a stack to evaluate Reverse Polish Notation (operators come after their operands: "3 4 +" means 3 + 4) — the core of how calculators and interpreters work.
Why it matters: it combines stacks, parsing and control flow into a real tool.
Finish the operator branch so "3 4 + 5 *" evaluates to 35.
Run your code — when the output matches the task, you will see a green check. Then mark the lesson complete.
Test your knowledgeA quick 3-question quiz on this lesson — instant feedback.
Ready for more? Optional paid resources that pick up where this lesson leaves off.
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