const add = function(a, b) {
	return a + b;
};

const subtract = function(a, b) {
	return a - b;
};

const sum = function(array) {
	let sumArray = 0;
  if (array.length == 0) {
    return 0;
  } else {
  for (let i = 0; i < array.length; i++) {
    sumArray += array[i];
  }
  return sumArray;
}
};

const multiply = function(numbers) {
  let multiplyNum = 1;
  for (let i = 0; i < numbers.length; i++) {
    multiplyNum *= numbers[i];
  }
  return multiplyNum;
};

const power = function() {
	
};

const factorial = function() {
	
};

// Do not edit below this line
module.exports = {
  add,
  subtract,
  sum,
  multiply,
  power,
  factorial
};