2015 AMC 8 Problems/Problem 10
Contents
[hide]Problem
How many integers between and have four distinct digits?
Solution 1
There are choices for the first number, since it cannot be , there are only choices left for the second number since it must differ from the first, choices for the third number, since it must differ from the first two, and choices for the fourth number, since it must differ from all three. This means there are integers between and with four distinct digits.
If you're too lazy to do , we can notice and The unit digit must be 6. Therefore the answer is the only answer with a a unit digit of 6. )
Video Solution (HOW TO THINK CRITICALLY!!!)
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Video solution
https://youtu.be/Zhsb5lv6jCI?t=272
https://www.youtube.com/watch?v=OESYIYjZFdk ~David
~savannahsolver
See Also
2015 AMC 8 (Problems • Answer Key • Resources) | ||
Preceded by Problem 9 |
Followed by Problem 11 | |
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 |
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