1. Let's clarify the problem and the solution you are referring to. 2. If the answer was expected to be 0 but you got 4, let's check the calculation step by step. 3. Suppose the problem was solving an equation or evaluating an expression that resulted in 4. 4. We need to identify where the mistake happened and correct it to get 0. 5. For example, if the problem was solving $x^2 - 4 = 0$, the solutions are $x = \pm 2$, not 0. 6. If the problem was evaluating $2 - 2$, the answer is 0, not 4. 7. Please provide the original problem or expression so I can help you find the correct answer and explain why it is 0, not 4.