Given expression: 6 3 2 4 + - *
Scan the expression from left to right:
6, 3, 2, 4: These are operands, so we push them onto a stack.
+: We encounter an operator. Pop the top two elements from the stack (4 and 2), add them (4 + 2 = 6), and push the result (6) back onto the stack.
-: We encounter another operator. Pop the top two elements from the stack (6 and 3), subtract them (3 - 6 = -3), and push the result (-3) back onto the stack.
: We encounter the last operator. Pop the top two elements from the stack (6 and -3), multiply them (6 -3 = -18), and push the result (-18) back onto the stack.
Since we've reached the end of the expression, the final result is the only element left on the stack, which is -18.
Therefore, the value of the postfix expression 6 3 2 4 + - * is -18.