**Fibonacci Series:** It is a series of numbers where the next term in series is the sum of the previous two numbers.

**Fibonacci Series:** 0 1 1 2 3 5 8 13 …

**Fibonacci Series Number in C++ using While Loop**

```
#include <iostream>
using namespace std;
int main()
{
int n,a,b,next;
cout<<"Enter a number to check if it is a Fibonacci Number: ";
cin>>n;
if(n==0||n==1)
cout<<n<<" is a fibonacci number\n\n";
else
a=0;b=1;
next=a+b;
while(next<n)
{
a=b;
b=next;
next=a+b;
}
if(next==n)
cout<<n<<" is a fibonacci number";
else
cout<<n<<" is not a fibonacci number";
return 0;
}
```

Output of Program

Enter a number to check if it is a Fibonacci Number: 10

10 is not a fibonacci number