2004 AMC 12A Problem 6

Compute each difference by factoring: $U - V = 2004^{2005},$ $V - W = 2004^{2004},$ $W - X = 2001 \cdot 2004^{2004},$ $X - Y = 2004^{2004},$ and $Y - Z = 2003 \cdot 2004^{2003}.$ Since $2004^{2005} = 2004 \cdot 2004^{2004}$ exceeds each of the others, none of which reaches $2004^{2005},$ the difference $U - V$ is the largest. Thus, the correct answer is A.