1993 AMC 8 Problem 20
Attempt Problem 20 of the 1993 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1993 AMC 8 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
20.
When is expressed as a single whole number, the sum of the digits is
Answer: D
Small hint:
is a followed by zeros; subtracting changes only the right end
Big hint:
The result is a block of nines ending in determine how many nines there are
Solution:
Subtracting from (a followed by zeros) gives a number that is nines followed by
The digit sum is
Thus, the correct answer is D .
Problem 20 in other years
- 1985 AMC 8
- 1986 AMC 8
- 1987 AMC 8
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