2021 JMPSC Invitationals Problems/Problem 15

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Problem

Abhishek is choosing positive integer factors of $2021 \times 2^{2021}$ with replacement. After a minute passes, he chooses a random factor and writes it down. Abhishek repeats this process until the first time the product of all numbers written down is a perfect square. Find the expected number of minutes it takes for him to stop.

Solution

8

See also

  1. Other 2021 JMPSC Invitational Problems
  2. 2021 JMPSC Invitational Answer Key
  3. All JMPSC Problems and Solutions

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