Date: Jan 2, 2005 4:39 PM
Author: Nat Silver
Subject: Re: Finding A, B, and C

Sylvain Croussette answered on alt.math.undergrad:
> st9468s4 (EJC)@drexel.edu wrote:

> ABC I have to find the values of A, B and C where A>B>C
>- CBA
>_________
>= CAB


Assuming A,B and C are single digits:
Rewrite as:
CAB
+CBA
--------
ABC

>From the 1st column: B+A=C, or B+A=C+10, if there is a carry.
From the 2nd column also A+B=B; this is the same as the 1st column
so it's impossible, unless there is a carry from the 1st; so it's
1+A+B=B+10, because A+B produced a carry in the 1st column.
From the third column 1+C+C=A.
Rewrite these equations:
1) A+B-C=10
2) A+B-B=9
3) A-2C=1
Clearly from equation 2, A=9, so from equation 3, C=4 so B=5.


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