2025 SSMO Relay Round 4 Problems
Problem 1
Call a positive integer chuzzed if the sum of the digits in its binary representation is equal to the units digit of its base- representation. Similarly, call a positive integer chopped if its binary representation does not contain two consecutive ones. Find the number of positive integers less than
 representation. Similarly, call a positive integer chopped if its binary representation does not contain two consecutive ones. Find the number of positive integers less than  that are chuzzed and chopped.
 that are chuzzed and chopped.
Problem 2
Let  Jonathan and Kate are playing a game with
 Jonathan and Kate are playing a game with  sticks. On each turn, a player may remove
 sticks. On each turn, a player may remove  
  or
 or  sticks. The player who picks up the last stick loses. Kate is first to remove sticks, and both players play optimally. For how many values of
 sticks. The player who picks up the last stick loses. Kate is first to remove sticks, and both players play optimally. For how many values of  in the range
 in the range ![$\left[T^3,2T^3\right]$](http://latex.artofproblemsolving.com/3/1/1/31124d3f1d2fe3a278328400cfd00e978855ca95.png) does Kate have a winning strategy?
 does Kate have a winning strategy?
Problem 3
Let  A particle moves in the coordinate plane such that at any time
 A particle moves in the coordinate plane such that at any time  its position is
 its position is ![\[\left(\sum_{a=1}^{T-1} \cos(at),\sum_{a=1}^{T-1} \sin(at)\right).\]](http://latex.artofproblemsolving.com/2/a/f/2aff036f84c6f9ae0cd1f2684885b7c4fc9f0a5d.png) Over the time interval
 Over the time interval ![$t\in(0,k],$](http://latex.artofproblemsolving.com/1/d/6/1d6e4f5955235095c51ab884b0552eb11476aea9.png) the particle lies on at least one coordinate axes
 the particle lies on at least one coordinate axes  times. If the minimal value of
 times. If the minimal value of  can be written as
 can be written as  for relatively prime positive integers
 for relatively prime positive integers  and
 and  find
 find  .
.
