AoPSWiki
Want to learn how to tackle those tough AMC/AIME/Olympiad counting and probability problems? Check out Art of Problem Solving's Intermediate Counting & Probability by David Patrick.
Personal tools

1995 AHSME Problems/Problem 13

From AoPSWiki

Problem

The addition below is incorrect. The display can be made correct by changing one digit d, wherever it occurs, to another digit e. Find the sum of d and e.

\begin{tabular}{ccccccc} & 7 & 4 & 2 & 5 & 8 & 6 \\+ & 8 & 2 & 9 & 4 & 3 & 0 ...

\mathrm{(A) \ 4 } \qquad \mathrm{(B) \ 6 } \qquad \mathrm{(C) \ 8 } \qquad \mathrm{(D) \ 10 } \qquad \mathrm{(E) \ \text{more...

Solution

If we change 0 only, it would be incorrect. The same for 1, but 2 we could change to 6. If we try all the other digits, we see that it would be impossible to correct the addition. Thus d=2 and e=6. d+e=\boxed{8\mathrm{(C)}}

See also

1995 AHSME (Problems)
Preceded by
Problem 12
Followed by
Problem 14
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 26 27 28 29 30
Our Precalculus course starts on Dec. 4. Master trig, complex numbers, and vectors and matrices in 2 and 3 dimensions. Click here to enroll today!
© Copyright 2008 AoPS Incorporated. All Rights Reserved. • FoundationPrivacyContact Us