document.write(`<h2>JS functions</h2>`)

/** for numbers from 5 to infinity
 * multiply a number by itself
 * add the number to it's product
 * divide the result by the same number
 */

// when the number = 5
  let result  = 5 * 5;
  result = result + 5;
  result = result/5;
  document.write(`<h3>result=${result}</h3>`);

  // when the number = 6
  result  = 6 * 6;
  result = result + 6;
  result = result/6;
  document.write(`<h3>result=${result}</h3>`);

  // when the number = 7
  result  = 7 * 7;
  result = result + 7;
  result = result/7;
  document.write(`<h3>result=${result}</h3>`);

  document.write(`Using functions`);

  // normal functions
  function operateNumber8() {
    let result  = 8 * 8;
    result = result + 8;
    result = result/8;
    document.write(`<h3>result=${result}</h3>`);
  }

  operateNumber8();
  operateNumber8();
  operateNumber8();
  operateNumber8();
  operateNumber8();

// functions that expect parameter/arguments
function operateANumber(numb) {
  let result  = numb * numb;
  result = result + numb;
  result = result/numb;
  document.write(`<h3>result for ${numb} = ${result}</h3>`);
}

operateANumber(9);
operateANumber(10);
operateANumber(11);
operateANumber(12);

// functions with a return type
function operateANumber(numb) {
  let result  = numb * numb;
  result = result + numb;
  result = result/numb;
  return result;
}

const result13  = operateANumber(13);
document.write(`<h3>so for 13, we have ${result13}</h3>`);

document.write(`<h3>and also for 14, we have ${operateANumber(14)}</h3>`);




// callback or arrow functions
const operateSomeNumber = (numb)=> ((numb * numb)+ numb)/numb;

const operateSomeNumberAgain = (numb)=> {
  let result  = numb * numb;
  result = result + numb;
  result = result/numb;
  return result;
};

document.write(`<h3>and also for 15, we have ${operateSomeNumber(15)}</h3>`);