SOLUTION: I'm thinking of an interesting number that I'll call N. When N has a 7 in front of it, the number formed is 5 times as large as when N has a 7 after it. The smallest number of digi

Question 1061453: I'm thinking of an interesting number that I'll call N. When N has a 7 in front of it, the number formed is 5 times as large as when N has a 7 after it. The smallest number of digits in N is:
a) 3 b)4 c)5 d)6 e)7
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
= number of digits has.
= with a added as a first digit
= with a added as a last digit
The problem says that

You could see what value of makes
a multiple of ,
but I want easier calculations
,
so I am looking for how to make a multiple of out of
,
which means being a multiple of 7.
does not work:

For ,
,
we find the first multiple of 7.
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