• Numbers: Type the number in "Type to output" box and click Output button to add it directly to the output.
• Opening parenthesis '(' and operators (+, -, *, /): Type in "Push to Stack" box and click Push button to add to the stack.
• Using the Pop button:
  • Step 1: Click the Pop button to remove the top element from the stack.
  • Step 2: Select To Output radio button if you want to add the popped element to the output (for operators like *, -, /).
  • Step 2 (Alternative): Select To Ignore radio button if you want to discard the popped element (for closing parenthesis ')').
• When you encounter ')': Pop the operator and select "To Output", then pop again and select "To Ignore" to remove the matching '('.
• Final step: Click Check button to verify if your postfix conversion is correct.

Example: For expression ( 5 + 3 ), the steps are:
1. Push '(' → Push '+' → Output 5 → Output 3
2. Pop and select "To Output" (outputs '+') → Pop and select "To Ignore" (removes '(')
3. Final output: 5 3 +