1. **State the problem:** Simplify the expression in the top-left rectangle: $17^2 - 286$. 2. **Recall the formula and rules:** Calculate the square of 17 and then subtract 286. 3. **Calculate $17^2$:** $$17^2 = 17 \times 17 = 289$$ 4. **Substitute and simplify:** $$289 - 286 = 3$$ 5. **Final answer:** The simplified value of $17^2 - 286$ is $3$.