Problem of the Week

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Marked Numbers

Posted: February 12, 2024

66 % of users got this correct

You have a large circle with the numbers 1 – 1000 written around the circle in order. Starting at 1, every 15^th numbers is marked (in other words, 1, 16, 31, and so on are marked). The marked numbers are not removed. The process is continued around and around the circle until all numbers that can be marked have been marked. How many numbers are marked?

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