# Concatenation of Consecutive Binary Numbers

Updated: Mar 25, 2021

Given an integer n, return *the decimal value of the binary string formed by concatenating the binary representations of *1

*to*n

*in order,*109 + 7.

**modulo**
**Example 1:**

**Input****:** n = 1 **Output****:** 1 **Explanation****:**** **"1" in binary corresponds to the decimal value 1.

**Example 2:**

**Input****:** n = 3
**Output****:** 27
**Explanation****:**** **In binary, 1, 2, and 3 corresponds to "1", "10", and "11". After concatenating them, we have "11011", which corresponds to the decimal value 27.

**Example 3:**

**Input****:** n = 12
**Output****:** 505379714
**Explanation**: The concatenation results in "1101110010111011110001001101010111100". The decimal value of that is 118505380540. After modulo 109 + 7, the result is 505379714.

**Constraints:**

1 <= n <= 105

**Solution:**

```
class Solution {
public int concatenatedBinary(int n) {
int mod = 1_000_000_007;
int result = 0,pow=1;
for(int i=n;i>0;i--)
{
int no = i;
while(no>0)
{
if((no&1)==1) result = (result+pow)%mod;
no=no>>1;
pow = (pow*2)%mod;
}
}
return result;
}
}
```