the sum of all values of n code example

Example 1: sum the all values from an array

var numbers = [3, 5, 7, 2];
var sum = numbers.reduce((x, y) => x + y);
console.log(sum); // returns 17

// other way

x = sumAll(1, 123, 500, 115, 44, 88);

function sumAll() {
  var i;
  var sum = 0;
  for (i = 0; i < arguments.length; i++) {
    sum += arguments[i];
  }
  return sum;
}

Example 2: formula for sum of n numbers

Sum of the First n Natural Numbers. We prove the formula 1+ 2+ ... + n = n(n+1) / 2, for n a natural number