# Demlo number (Square of 11…1)

Given a number of the form 11..1 such that number of digits in it is smaller than 10, find square of the number.

Examples:

```Input : 111111
Output : 12345654321

Input : 1111
Output : 1234321
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Squares of 11…1 (where length is smaller than 10) are called Demlo numbers. A demlo number is number which consist of 1, 2, 3….n, n-1, n-2, …..1.
Demlo numbers are:

```1 = 1
11 * 11 = 121
111 * 111 = 12321
1111 * 1111 = 1234321
```

To find demlo number, first we find append n numbers which are increasing and then append numbers which are decreasing.

## C++

 `// CPP program to print DemloNumber ` `#include ` `using` `namespace` `std; ` ` `  `// To return demlo number. This function assumes ` `// that the length of str is smaller than 10. ` `string printDemlo(string str) ` `{ ` `    ``int` `len = str.length(); ` `    ``string res = ``""``; ` ` `  `    ``// Add numbers to res upto size ` `    ``// of str and then add number ` `    ``// reverse to it ` `    ``for` `(``int` `i = 1; i <= len; i++) ` `        ``res += ``char``(i + ``'0'``); ` ` `  `    ``for` `(``int` `i = len - 1; i >= 1; i--) ` `        ``res += ``char``(i + ``'0'``); ` ` `  `    ``return` `res; ` `} ` ` `  `// Driver program to test printDemlo() ` `int` `main() ` `{ ` `    ``string str = ``"111111"``; ` `    ``cout << printDemlo(str); ` `    ``return` `0; ` `} `

## Java

 `// Java program to print DemloNumber ` `public` `class` `Main { ` ` `  `    ``// To return demlo number. This function assumes ` `    ``// that the length of str is smaller than 10. ` `    ``static` `String printDemlo(String str) ` `    ``{ ` `        ``int` `len = str.length(); ` `        ``String res = ``""``; ` ` `  `        ``// Add numbers to res upto size ` `        ``// of str and then add number ` `        ``// reverse to it ` `        ``for` `(``int` `i = ``1``; i <= len; i++) ` `            ``res += Integer.toString(i); ` ` `  `        ``for` `(``int` `i = len - ``1``; i >= ``1``; i--) ` `            ``res += Integer.toString(i); ` ` `  `        ``return` `res; ` `    ``} ` ` `  `    ``// Driver program to test printDemlo() ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``String str = ``"111111"``; ` `        ``System.out.println(printDemlo(str)); ` `    ``} ` `} `

## Python

 `# Python program to print Demlo Number ` ` `  `# To return demlo number ` `# Length of s is smaller than 10 ` `def` `printDemlo(s): ` `    ``l ``=` `len``(s) ` `    ``res ``=` `"" ` `     `  `    ``# Add numbers to res upto size ` `    ``# of s then add in reverse ` `     `  `    ``for` `i ``in` `range``(``1``,l``+``1``): ` `        ``res ``=` `res ``+` `str``(i) ` `     `  `    ``for` `i ``in` `range``(l``-``1``,``0``,``-``1``): ` `        ``res ``=` `res ``+` `str``(i) ` `     `  `    ``return` `res ` `     `  ` `  `# Driver Code ` `s ``=` `"111111"`     `print` `printDemlo(s) ` ` `  `# Contributed by Harshit Agrawal `

## C#

 `// C# program to print DemloNumber ` `using` `System; ` `public` `class` `GFG { ` ` `  `    ``// To return demlo number. This function assumes ` `    ``// that the length of str is smaller than 10. ` `    ``static` `String printDemlo(String str) ` `    ``{ ` `        ``int` `len = str.Length; ` `        ``String res = ``""``; ` ` `  `        ``// Add numbers to res upto size ` `        ``// of str and then add number ` `        ``// reverse to it ` `        ``for` `(``int` `i = 1; i <= len; i++) ` `            ``res += i.ToString(); ` ` `  `        ``for` `(``int` `i = len - 1; i >= 1; i--) ` `            ``res += i.ToString(); ` ` `  `        ``return` `res; ` `    ``} ` ` `  `    ``// Driver program to test printDemlo() ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``String str = ``"111111"``; ` `        ``Console.WriteLine(printDemlo(str)); ` `    ``} ` `} ` `// This code is contributed by mits `

## PHP

 `= 1; ``\$i``--) ` `        ``\$res` `.= ``chr``(``\$i` `+ 48); ` ` `  `    ``return` `\$res``; ` `} ` ` `  `// Driver Code ` `\$str` `= ``"111111"``; ` `echo` `printDemlo(``\$str``); ` ` `  `// This code is contributed by mits ` `?> `

Output:

```12345654321
```

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Improved By : Mithun Kumar

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