2010 AMC 10B Problem 1

We have that $$\begin{aligned}100(100 - 3) &= 100 \cdot 97 \\&= 9700\end{aligned}$$ and $$\begin{aligned}100 \cdot 100 - 3 &= 10000 - 3\\ &= 9997.\end{aligned}$$ As such, their difference is: $$9700 - 9997 = - 297.$$ Thus, C is the correct answer.