## Sum of First N Natural Numbers

To find the sum of first N natural numbers in Dart, we may use the direct mathematical formula, or use a For loop to iterate from 1 to N and accumulate the sum. In this tutorial, we will write programs using each of the said approaches.

## Dart Program

### Find the sum using For Loop

In the following program, we read a number into `n`, and find the sum of first n natural numbers using a For Loop.

main.dart

```import 'dart:io';

void main(){
//read number from user
print('Enter n');
var n = int.parse(stdin.readLineSync()!);

//initialize sum to 0
var sum = 0;

for(var i = 1; i <= n; i++) {
sum += i;
}

print('sum = \$sum');
}
```

Output

```Enter n
10
sum = 55
```

### Find the sum using mathematical formula

In the following program, we read a number into `n`, and find the sum of first n natural numbers using the below formula.

```sum = n * (n + 1) / 2
```

main.dart

```import 'dart:io';

void main(){
//read number from user
print('Enter n');
var n = int.parse(stdin.readLineSync()!);

var sum = n * (n + 1) / 2;
print('sum = \$sum');
}
```

Output

```Enter n
10
sum = 55.0
```

## Conclusion

In this Dart Tutorial, we learned how to find the sum of first n natural numbers.