SOLUTION: There is a number that is two times the sum of it's digits. What is this number?

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Question 284878: There is a number that is two times the sum of it's digits. What is this number?
Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=tens digit
And let y=units digit
Sum of the digits=x+y
two times the sum=2(x+y)
The number then is:10x+y, so;
10x+y=2(x+y) simplify
10x+y=2x+2y subtract 2x and also y from each side
10x-2x+y-y=2x-2x+2y-y collect like terms
8x=y divide each side by x
y/x=8
If y=8 then x=1 ---the number is 18; sum of the digits is 9 and 2*9=18
Can't be a 3-digit or larger number. Do you know why?
Hope this helps---ptaylor