# 2003 AMC 8 Problems/Problem 23

## Problem

In the pattern below, the cat moves clockwise through the four squares, and the mouse moves counterclockwise through the eight exterior segments of the four squares.

If the pattern is continued, where would the cat and mouse be after the 247th move?

## Solution

Break this problem into two parts: where the cat will be after the $247^{th}$ move, and where the mouse will be.

The cat has four possible positions in 1 cycle which are repeated every four moves. $247$ has a remainder of $3$ when divided by $4$. This corresponds to the position the cat has after the 3rd move, which is the bottom right corner.

Similarly, the mouse has eight possible positions in 1 cycle that repeat every eight moves. $247$ has a remainder of $7$ when divided by $8$. This corresponds to the position the rat has after the 7th move which is bottom left corner.

The only arrangement with the mouse in that position and the cat in the bottom right square is $\boxed{\textbf{(A)}}$.

## Video Solution

https://youtu.be/RCUzhVOi7XI ~DSA_Catachu

## Video Solution #2

https://youtu.be/xMy3wMFF3KQ Soo, DRMS, NM

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. 