Maths Olympiad Prep

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Algebra Difficulty 4.9 AIME Prove it United States

Problem:

Consider the addition problem:

CASH
+ME
OSIDE

where each letter represents a base-ten digit, and C,M,O0C, M, O \neq 0. (Distinct letters are allowed to represent the same digit) How many ways are there to assign values to the letters so that the addition problem is true?

Solution

Solution:

Clearly, CASHC A S H and MEM E cannot add up to 1100011000 or more, so O=1O=1 and S=0S=0. By examining the units digit, we find that H=0H=0. Then CASH+ME<9900+99<10000C A S H+M E<9900+99<10000, so there are no solutions.

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Source: MathNet, licensed CC-BY-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.