2020 AMC 8 Problem 7
Attempt Problem 7 of the 2020 AMC 8 below, then check your answer against the video solution and professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2020 AMC 8 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
7.
How many integers between and have four distinct digits arranged in increasing order? (For example, is one such integer.)
Answer: C
Small hint:
The first two digits must be and
Big hint:
Choose the last two digits from
Video solution:
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Written solution:
The thousands digit must be Since the digits are distinct and increasing, the hundreds digit must be
The last two digits must be chosen from Once the two digits are chosen, their order is forced.
There are such integers.
Thus, the correct answer is C.
Problem 7 in other years
- 1985 AMC 8
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