The 5-Digit Number
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pending
There is an interesting 5-digit number A. With a 1 after it, it is three times as large as with a 1 before it. What is A?
The answer is 42857.
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1 solution
The original number is 'A'
Now, A with a 1 before it is : 100000 + A
and A with a 1 after it is : 10A + 1
According to the question, with a 1 after it, it is 3 times as large as with a 1 before it.
thus
10A + 1 = 3 ( 100000 + A)
or, 10A + 1 = 300000 + 3A
or, 7A = 300000 - 1
or, 7A = 299999
or A = 299999/7
or, A = 42857
Therefor, the 5 digit number A is 42857