(HELP/LOST)Generate Random Whole Numbers within a Range

JavaScript
1

Generate Random Whole Numbers within a Range
Instead of generating a random number between zero and a given number like we did before, we can generate a random number that falls within a range of two specific numbers.

To do this, we’ll define a minimum number min and a maximum number max.

Here’s the formula we’ll use. Take a moment to read it and try to understand what this code is doing:

Math.floor(Math.random() * (max - min + 1)) + min

Instructions

Create a function called randomRange that takes a range myMin and myMax and returns a random number that’s greater than or equal to myMin, and is less than or equal to myMax, inclusive.

// Example

  return 0; // Change this line

}function ourRandomRange(ourMin, ourMax) {

  return Math.floor(Math.random() * (ourMax - ourMin + 1)) + ourMin;
}

ourRandomRange(1, 9);

// Only change code below this line.

function randomRange(myMin, myMax) {

// Example

  return 0; // Change this line

}function ourRandomRange(ourMin, ourMax) {

  return Math.floor(Math.random() * (ourMax - ourMin + 1)) + ourMin;
}

ourRandomRange(1, 9);

**// Only change code below this line.**

function randomRange(myMin, myMax) {


// Change these values to test your function
var myRandom = randomRange(5, 15);


// Change these values to test your function
var myRandom = randomRange(5, 15);
Build a Fortune Teller - Build a Fortune Teller
2

I cleaned up your code.
You need to use triple backticks to post code to the forum.
See this post for details.

1 Like
3

Thanks. Just learned something new.

Do you have a solution to my problem? I looked at some other users explanation, but couldn’t figure it out.

4

The essence of the challenge is to understand what this code does.

Math.floor(Math.random() * (max - min + 1)) + min

It produces a random whole number in a range, with the value of min being the smallest possible number and max the largest possible number.

If you looked at the example in the ourRandomRange function, you’ll find that it’s identical to the above piece of code, but with a few names changed.

5 Likes
5

Okay, got it. Thank You.

I changed the name of the values to correspond with the values named in the randomRange function and ta-da it worked.

1 Like
6

Would you be able to explain what this is exactly doing?

(max - min + 1)
7

It’s the “distance” between the lowest and highest points of your range. It doesn’t make sense to explain it out of context, so I’ll explain the whole thing.

If min is 2 and max is 5, the “distance” from each other is 5 - 2 + 1 = 4. Then multiplying that by the result of Math.random() (a number from 0 up to, but not including 1), you’ll get a number from 0 up to, but not including 4.

Now you plug that number to the Math.floor function, which drops the decimal part of the number (if it’s positive), so you now have the integers 0, 1, 2 and 3.

At the end, you add the value of min, so you now have the integers 2, 3, 4 and 5, which are all of the integers in the range from 2 to 5.

If you removed the + 1 from (max - min + 1), you’ll only get the integers 2, 3 and 4, which is fine if you don’t want to include max in the numbers that you want to get.

34 Likes
I don't get the range concept - Math.random() * (max - min + 1)) + min
8

Awesome! Thanks so much for the information. Clarifies a bunch!

9

Terrific explanation, thanks!

11

That was an awesome explanation, thank you @kevcomedia. It bent my brain trying to understand the concept of ‘distance’ but it finally sank in!
Thanks again!

2 Likes
12

This is the best explanation I’ve seen so far—thank you. I’ve seen many “just do it like this,” but nobody so far has said, “this is how the math works.” You’ve helped my weary brain.

2 Likes