Difference between revisions of "2024 SSMO Speed Round Problems/Problem 2"

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==Solution==
 
==Solution==
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Suppose that there <math>x</math> toys. Since <math>x</math> toys can be split equally when 4 of 5 students are present, <math>x</math> must be a multiple of <math>\text{lcm}(4,5) = 20.</math> So, <math>x</math> can be <math>20,40,60,\dots.</math> Now, since there is one toy left over when the toys are split when <math>3</math> students are present, <math>x</math> must be one greater than a multiple of <math>3.</math> As <math>20 = 3\cdot6+2</math> and <math>40 = 3\cdot13+1,</math> we conclude that the answer is <math>\boxed{40}.</math>
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~SMO_Team

Latest revision as of 14:25, 10 September 2025

Problem

Gracie's students play with some toys. When 4 or 5 students are present, the toys can be equally distributed to everyone. However, when there are only 3 students, there is one toy leftover after giving everyone the same number of toys. What is the least possible number of toys that Gracie could have?

Solution

Suppose that there $x$ toys. Since $x$ toys can be split equally when 4 of 5 students are present, $x$ must be a multiple of $\text{lcm}(4,5) = 20.$ So, $x$ can be $20,40,60,\dots.$ Now, since there is one toy left over when the toys are split when $3$ students are present, $x$ must be one greater than a multiple of $3.$ As $20 = 3\cdot6+2$ and $40 = 3\cdot13+1,$ we conclude that the answer is $\boxed{40}.$

~SMO_Team