Difference between revisions of "2002 OIM Problems/Problem 1"

 
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== Problem ==
 
== Problem ==
The integers from 1 to 2002, both inclusive, are written on a blackboard in increasing order <math>1, 2, \cdots , 2001, 2002</math>. Then, those in first, fourth place, seventh place, etc. are deleted, that is, those who occupy the places of the form <math>3k + 1</math>. In the new list the numbers that are in the places of the form <math>3k + 1</math> are deleted.  This process is repeated until all numbers are deleted from the list. What was the last number that was deleted?
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The integers from 1 to 2002, both inclusive, are written on a blackboard in increasing order <math>1, 2, \cdots , 2001, 2002</math>. Then, those in first, fourth place, seventh place, etc. are erased, that is, those who occupy the places of the form <math>3k + 1</math>. In the new list the numbers that are in the places of the form <math>3k + 1</math> are erased.  This process is repeated until all numbers are deleted from the list. What was the last number that was erased?
  
 
~translated into English by Tomas Diaz. ~orders@tomasdiaz.com
 
~translated into English by Tomas Diaz. ~orders@tomasdiaz.com

Latest revision as of 03:38, 14 December 2023

Problem

The integers from 1 to 2002, both inclusive, are written on a blackboard in increasing order $1, 2, \cdots , 2001, 2002$. Then, those in first, fourth place, seventh place, etc. are erased, that is, those who occupy the places of the form $3k + 1$. In the new list the numbers that are in the places of the form $3k + 1$ are erased. This process is repeated until all numbers are deleted from the list. What was the last number that was erased?

~translated into English by Tomas Diaz. ~orders@tomasdiaz.com

Solution

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See also