2000 AMC 8 Problem 9

Attempt Problem 9 of the 2000 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 2000 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

9.

Three-digit powers of 22 and 55 are used in this ''cross-number'' puzzle. What is the only possible digit for the outlined square? 2. 2m1. 5n\begin{array}{lcl} \boldsymbol{\rightarrow} & & \boldsymbol{\downarrow} \\ \textbf{2. } 2^m & & \textbf{1. } 5^n \end{array}

00

22

44

66

88

Answer: D
Concepts:digitssystematic listing
Difficulty rating: 1020
Solution:

The only 33-digit powers of 55 are 125125 and 625.625. This means that the 22 spot is filled with a 2.2.

The only 33-digit power of 22 beginning with a 22 is 256,256, so the outlined square is filled with a 6.6.

Thus, D is the correct answer.

← Problem 8#8
Full Exam

Problem 9 in Other Years

1985 AMC 8 · 1986 AMC 8 · 1987 AMC 8 · 1988 AMC 8 · 1989 AMC 8 · 1990 AMC 8 · 1991 AMC 8 · 1992 AMC 8 · 1993 AMC 8 · 1994 AMC 8 · 1995 AMC 8 · 1996 AMC 8 · 1997 AMC 8 · 1998 AMC 8 · 1999 AMC 8 · 2001 AMC 8 · 2002 AMC 8 · 2003 AMC 8 · 2004 AMC 8 · 2005 AMC 8 · 2006 AMC 8 · 2007 AMC 8 · 2008 AMC 8 · 2009 AMC 8 · 2010 AMC 8 · 2011 AMC 8 · 2012 AMC 8 · 2013 AMC 8 · 2014 AMC 8 · 2015 AMC 8 · 2016 AMC 8 · 2017 AMC 8 · 2018 AMC 8 · 2019 AMC 8 · 2020 AMC 8 · 2022 AMC 8 · 2023 AMC 8 · 2024 AMC 8 · 2025 AMC 8 · 2026 AMC 8