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counting stones


Nine stones are arranged in a straight line. They are counted from left to right as 1,2,3,..., 9 and then from right to left so that the stone previously counted as 8 is counted as 10.The pattern is continued to the left until the stone previously counted as 1 is counted as17. The pattern then reverses so that the stone originally counted as 2 (then 16) is counted as 18, 3 as 19,and so on. The counting continues in this way. Which of the original stones is counted as 599? Express your answer as the first number assigned to that stone.

(Source: Adapted from Mathematics Teaching in the Middle School, May 1997)

 

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