I found a challenge where I have to create Multiply, Exponent, Factorial, and Fibonacci Sequence functions without operators/built in functions other than this block of code

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function add(x, y) {
  return (sum = x   y);
}

So far, I only know how to do them using recursive functions with the (-) operator but that won't be accepted. I am completely lost as to how to go about this. The hint was to use a loop. We also cannot use or --

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This is what I have so far but they don't meet the criteria.

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function multiply(x, y) {
  let n = x;
  for (let i = 1; i < y; i  = 1) x  = n;
  return x;
}

function exponent(x, n) {
  if (n === 0) {
    return 1;
  } else {
    return multiply(x, exponent(x, n - 1));
  }
}

function factorial(x) {
  if (x === 0) {
    return 1;
  } else {
    return multiply(x, factorial(x - 1));
  }
}

function fibonacci(n) {
  if (n <= 1 || n === NaN || n % 1 !== 0) {
    return 1;
  } else {
    return fibonacci(n - 1)   fibonacci(n - 2);
  }