alue of the postfix expression 6 8 2 1 + – *

Sure, here is the step by step solution for the postfix expression 6 8 2 1 + - *:

1. Scan the expression from left to right.
2. When you encounter numbers, push them onto the stack.
3. When you encounter an operator, pop the last two numbers from the stack and perform the operation.
4. Push the result back onto the stack.
5. Continue this process until you have scanned the entire expression.
6. The final result will be the only number left on the stack.

Let's apply these steps to your expression:

1. Push 6 onto the stack.
2. Push 8 onto the stack.
3. Push 2 onto the stack.
4. Push 1 onto the stack.
5. Encounter '+', so pop 1 and 2 from the stack, add them to get 3. Push 3 back onto the stack.
6. Encounter '-', so pop 3 and 8 from the stack, subtract 3 from 8 to get 5. Push 5 back onto the stack.
7. Encounter '*', so pop 5 and 6 from the stack, multiply them to get 30. Push 30 back onto the stack.

So, the value of the postfix expression 6 8 2 1 + - * is 30.