Question

Evaluate using stack 10, 3,*,30,2,*,-

Answer 1

Scan the expression from left to right and use a stack. Push 10 and 3; multiply them to get 30. Then push 30 and 2; multiply them to get 60. Finally, subtract the second popped value from the first popped value: 30 − 60 = −30. Therefore, the final answer is −30.

Operator/Operand	Stack	Calculation	Meaning
10	10		Operand pushed to stack
3	10, 3		Operand pushed to stack
*	30	10 × 3 = 30	Pop last two operands, perform the operation and push the result onto stack
30	30, 30		Operand pushed to stack
2	30, 30, 2		Operand pushed to stack
*	30, 60	30 × 2 = 60	Pop last two operands, perform the operation and push the result onto stack
-	-30	30 − 60 = -30	Pop last two operands, perform the operation and push the result onto stack