Without using a calculator, compute $1002^2-502^2+298^2-202^2$.
I notice that this problem involves the difference of squares, which can be factored as $(a^2-b^2) = (a+b)(a-b)$. Maybe I can use this formula to simplify the expressions inside the parentheses. For example, $1002^2-502^2 = (1002+502)(1002-502) = 1504 \cdot 500 = 752000$. Similarly, $298^2-202^2 = (298+202)(298-202) = 500 \cdot 96 = 48000$. So the original problem becomes $752000 + 48000$, which is much easier to compute. I can add these numbers by lining up the digits and adding from right to left, carrying over when needed. I get $752000 + 48000 = 800000$.

