2024 AMC 8 Problems/Problem 4
Contents
- 1 Problem
- 2 Solution
- 3 Video Solution by Central Valley Math Circle (Goes through the full thought process)
- 4 Video Solution by Math-X (First fully understand the problem!!!)
- 5 Video Solution (A Clever Explanation You’ll Get Instantly)
- 6 Video Solution 1 (Simple and Fast) by Parshwa
- 7 Video Solution 2 (easy to digest) by Power Solve
- 8 Video Solution by Math-X (First fully understand the problem!!!)
- 9 Video Solution by NiuniuMaths (Easy to understand!)
- 10 Video Solution 2 by SpreadTheMathLove
- 11 Video Solution by CosineMethod [🔥Fast and Easy🔥]
- 12 Video Solution by Intersigation
- 13 Video Solution by Daily Dose of Math (Understandable, Logical, and Speedy)
- 14 Video Solution by WhyMath
- 15 See Also
Problem
When Yunji added all the integers from 
to 
, she mistakenly left out a number. Her incorrect sum turned out to be a square number. What number did Yunji leave out?
Solution
Adding numbers 1 through 9 gives us 45. This was her expected sum, but what she got was a perfect square. Since she got that perfect square sum by forgetting a number, that sum is less than 45. The square number right under 45 is 36. So 45 - 36 = 9. So the solution is E[9].
~That_One_Dude
Video Solution by Central Valley Math Circle (Goes through the full thought process)
~mr_mathman
Video Solution by Math-X (First fully understand the problem!!!)
https://youtu.be/BaE00H2SHQM?si=tzbzeCdEfXqROciK&t=907
~Math-X
Video Solution (A Clever Explanation You’ll Get Instantly)
https://youtu.be/5ZIFnqymdDQ?si=bxVKQiul4AjzVUgC&t=331
~hsnacademy
Video Solution 1 (Simple and Fast) by Parshwa
Video Solution 2 (easy to digest) by Power Solve
https://youtu.be/HE7JjZQ6xCk?si=sTC7YNSmfEOMe4Sn&t=179
Video Solution by Math-X (First fully understand the problem!!!)
https://youtu.be/BaE00H2SHQM?si=9ZUxEGmGam7il9xr&t=907
~Math-X
Video Solution by NiuniuMaths (Easy to understand!)
https://www.youtube.com/watch?v=Ylw-kJkSpq8
~NiuniuMaths
Video Solution 2 by SpreadTheMathLove
https://www.youtube.com/watch?v=L83DxusGkSY
Video Solution by CosineMethod [🔥Fast and Easy🔥]
Video Solution by Intersigation
https://youtu.be/ktzijuZtDas&t=232
Video Solution by Daily Dose of Math (Understandable, Logical, and Speedy)
https://youtu.be/bSPWqeNO11M?si=HIzlxPjMfvGM5lxR
~Thesmartgreekmathdude
Video Solution by WhyMath
See Also
| 2024 AMC 8 (Problems • Answer Key • Resources) | ||
| 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 AJHSME/AMC 8 Problems and Solutions | ||
The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. 
