3816547290

A Special Number: the only one in which

```
Every digit is used,
Each digit is used only once, and
The first n digits are divisible by n, for n=1..10.
```

3 is divisible by 1,

38 is divisible by 2,

381 is divisible by 3,

3816 is divisible by 4,

38165 is divisible by 5,

381654 is divisible by 6,

3816547 is divisible by 7,

38165472 is divisible by 8,

381654729 is divisible by 9,

3816547290 is divisible by 10.

## Comments

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TopNewestOn Brilliant there are question related to this number. This number can found out without hit-n-trial method.

Clearly the 5th and 10th digits are 5 & 0 respectively,

Now 4th digit can only be from 2 & 6 as 3rd digit is odd and for the number to be divisible by 4 its last two digits must be divisible by 4,

Sum of first 3, next 3 & next 3 digits must be divisible by 3,

Hence,

We get the following combinations for 4th,5th &6th digits - 258 or 654,

Now with use of divisibility of 8 we can figure out 6th,7th & 8th digits,

With help of less hard work we can figure out the number. – Akshay Yadav · 1 year, 10 months ago

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Similarly , as \(8\) is divisible by \(4\) the \(8^{th}\) digit would be either \(2\) or \(4\). Then, as

\(Akshay\)told we can proceed to get the answer. – Akshat Sharda · 1 year, 9 months agoLog in to reply

– Ayush Verma · 1 year, 10 months ago

Hmmm... Well answered brother.. ThankssLog in to reply

Good job, Falzan! – Jeganathan Sriskandarajah · 1 year, 9 months ago

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i've always been intersred in relation between numbers .... awesome !! – Ahmed Salah · 1 year, 9 months ago

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By the way I already knew that number. – Akshat Sharda · 1 year, 9 months ago

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Wow, beautiful! – Tabula Rasa · 1 year, 9 months ago

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That's brilliant – Sriram Venkatesan · 1 year, 10 months ago

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Great Work.. Its Awesome// how did you found it? – Ayush Verma · 1 year, 10 months ago

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