help stuck

I don't know where to add the 5.

script.js
function random_number(num) {  // New function called random_choice that takes one parameter, num (or a number)
// Get a random number between 0 and a passed-in number
var num =num || 4  // If no number passed in, default to 4
return Math.floor(Math.random() * num); // Round the answer down (floor) of a random number between 0 and 1 and multiply it by a number. Then return a value and exit the function.
}

function mash_choice() {  // New function called mash_choice that doesn't take any parameters
// Since MASH is a special case, give it its own list
var mash = ['boat', 'plane', 'RV', 'motorcycle', 'bicycle'];  // The array of choices to pick from
var randomNum = random_number(4);  // Use the above function to get a number between 0 and 4
return mash[randomNum];  // Return the list item the random number function just picked and exit the function
}

// Get a random answer from the available answers in a given category
var choices = [];  // A blank array to hold the user provided answer
var selector = 'input[name="' + category + '[]"]';  // Build a CSS selector for the blanks in our passed in category
var inputs = document.querySelectorAll(selector);  // Get all of the inputs that match our selector

for (var i = 0; i < inputs.length; i++) {  // Begin a for loop that will run through the code. i++ = add one to the counter which is "i"
answer = inputs[i].value;  // Get the input with the index value of the counter and get the value ie. if they typed in dog, you get back "dog"
if (answer !== '') {  // If answer doesn't equal a blank... !== means doesn't equal
choices.push(answer); //...add it to the end of the list
}
}
return choices[random_number(choices.length)];   // Pick and return a random choice choice.length = number of answers the user provided in that category
}

// Find the spans that need filled
var home = document.querySelector('#home');  // This says make a new variable and find the HTML tag that has the ID of "home"
var profession = document.querySelector('#profession');
var pet = document.querySelector('#pet');
var location = document.querySelector('#location');

// Fill them with the provided answers
home.innerHTML = answers.mash;  // Change the content of the element in the HTML doc with the id "home" to the "mash" value in answers
profession.innerHTML = answers.profession;  // Change the content of the element in the HTML doc with the id "career" to the "career" value in answers
}

function handle_submission(evt) {
evt.preventDefault();  // Stop the form from reloading the page
evt.stopPropagation();  // Stop the form from reloading the page

// Build up our answers object
var answers = {
'mash': mash_choice(),
}
// Fill in the answers

}

// Find the form on the page and attach a handler for when it's submitted
var form = document.querySelector('#mash');
form.addEventListener('submit', handle_submission);  // Anytime the form is submitted, we want to call the function handle_submission
index.html
<!DOCTYPE html>
<html lang="en">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=0.5, maximum-scale=0.5, minimal-ui">
<title>MASH</title>

<body>
<form action="" method="post" id="mash">
<h1 class="title">MASH</h1>
<p class="sub-title">Make sure to list five under each category.</p>

<div class="choice-bucket">
<h4 class="highlight">What will your profession be?</h4>
<input name="career[]">
<input name="career[]">
<input name="career[]">
<input name="career[]">
<input name="career[]">
</div>

<div class="choice-bucket">
<h4 class="highlight">What kind of animal will you have?</h4>
<input name="pet[]">
<input name="pet[]">
<input name="pet[]">
<input name="pet[]">
<input name="pet[]">
</div>

<div class="choice-bucket">
<h4 class="highlight">Where will you live?</h4>
<input name="location[]">
<input name="location[]">
<input name="location[]">
<input name="location[]">
<input name="location[]">
</div>
<div class="choice-bucket">
<h4 class="highlight">What kind of car will you have?</h4>
<input name="car[]">
<input name="car[]">
<input name="car[]">
<input name="car[]">
<input name="car[]">
</div>

<input type="submit" value="Tell My Future">
</form>

<h3>You will live in a <span id="home"></span></h3>
<h3>You will be a <span id="career"></span></h3>
<h3>You will have a <span id="pet"></span></h3>
<h3>You will live in <span id="location"></span></h3>
<h3>You will drive a <span id="car"></span></h3>
</div>

<script src="script.js"></script>
</body>
</html> 