Difference between revisions of "2024 AMC 10A Problems/Problem 5"

 
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<math>\textbf{(A) } 11\qquad\textbf{(B) } 21\qquad\textbf{(C) } 22\qquad\textbf{(D) } 23\qquad\textbf{(E) } 253</math>
 
<math>\textbf{(A) } 11\qquad\textbf{(B) } 21\qquad\textbf{(C) } 22\qquad\textbf{(D) } 23\qquad\textbf{(E) } 253</math>
  
== Solution 1==
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== Solution==
 
Note that <math>2024=2^3\cdot11\cdot23</math> in the prime factorization. Since <math>23!</math> is a multiple of <math>2^3, 11,</math> and <math>23,</math> we conclude that <math>23!</math> is a multiple of <math>2024.</math> Therefore, we have <math>n=\boxed{\textbf{(D) } 23}.</math>
 
Note that <math>2024=2^3\cdot11\cdot23</math> in the prime factorization. Since <math>23!</math> is a multiple of <math>2^3, 11,</math> and <math>23,</math> we conclude that <math>23!</math> is a multiple of <math>2024.</math> Therefore, we have <math>n=\boxed{\textbf{(D) } 23}.</math>
  
~MRENTHUSIASM
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<u><b>Remark</b></u>
  
Note: This is another example where knowing the prime factorization of the year is very useful
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Memorizing the prime factorization of the current year is useful for the AMC 8/10/12 Exams.
  
== Solution 2 (very similar to Solution 1)==
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~MRENTHUSIASM
Again, note that the prime factorization of 2024 is <math>2^3\cdot11\cdot23</math>. We know that for a factorial to contain a prime number <math>n</math>, it must be at least <math>n!</math>. Therefore, we have <math>n=\boxed{\textbf{(D) } 23}.</math>
 
  
~FRANKLIN2013
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== Video Solution by Pi Academy ==
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https://youtu.be/GPoTfGAf8bc?si=JYDhLVzfHUbXa3DW
  
 
== Video Solution by Daily Dose of Math ==
 
== Video Solution by Daily Dose of Math ==
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== Video Solution 1 by Power Solve ==
 
== Video Solution 1 by Power Solve ==
 
https://youtu.be/j-37jvqzhrg?si=qwyiAvKLbySyDR7D&t=529
 
https://youtu.be/j-37jvqzhrg?si=qwyiAvKLbySyDR7D&t=529
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==Video Solution by SpreadTheMathLove==
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https://www.youtube.com/watch?v=6SQ74nt3ynw
  
 
==See also==
 
==See also==

Latest revision as of 08:55, 15 November 2024

The following problem is from both the 2024 AMC 10A #5 and 2024 AMC 12A #4, so both problems redirect to this page.

Problem

What is the least value of $n$ such that $n!$ is a multiple of $2024$?

$\textbf{(A) } 11\qquad\textbf{(B) } 21\qquad\textbf{(C) } 22\qquad\textbf{(D) } 23\qquad\textbf{(E) } 253$

Solution

Note that $2024=2^3\cdot11\cdot23$ in the prime factorization. Since $23!$ is a multiple of $2^3, 11,$ and $23,$ we conclude that $23!$ is a multiple of $2024.$ Therefore, we have $n=\boxed{\textbf{(D) } 23}.$

Remark

Memorizing the prime factorization of the current year is useful for the AMC 8/10/12 Exams.

~MRENTHUSIASM

Video Solution by Pi Academy

https://youtu.be/GPoTfGAf8bc?si=JYDhLVzfHUbXa3DW

Video Solution by Daily Dose of Math

https://youtu.be/DXDJUCVX3yU

~Thesmartgreekmathdude

Video Solution 1 by Power Solve

https://youtu.be/j-37jvqzhrg?si=qwyiAvKLbySyDR7D&t=529

Video Solution by SpreadTheMathLove

https://www.youtube.com/watch?v=6SQ74nt3ynw

See also

2024 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 4
Followed by
Problem 6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 10 Problems and Solutions
2024 AMC 12A (ProblemsAnswer KeyResources)
Preceded by
Problem 3
Followed by
Problem 5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AMC 12 Problems and Solutions

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