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JavaScript JavaScript Basics (Retired) Working With Numbers The Random Challenge Solution

Bianca Power
Bianca Power
8,094 Points
Posted by Bianca Power
Bianca Power
8,094 Points

Question about the maths

I'm wondering why we can't just do what I've done... clearly it's wrong otherwise there wouldn't have been a more complicated version as the "solution" :P

My workspace: https://w.trhou.se/5ee0hav2fo

2 Answers

Damien Watson
Damien Watson
27,419 Points
Damien Watson
Damien Watson
27,419 Points

Hi Bianca,

I'm not sure what the video shows, but you are very close to the solution. Using:

//EXT: collect 2 numbers, and generate a random number between the two
var usrNum1 = 4;
var usrNum2 = 10;
var randNum = Math.floor(Math.random() * usrNum2) + usrNum1;

The key is 'between the two'... a random between 4 and 10 for example.

Math.random() * usrNum2 will return decimal numbers between 0.0 and 9.9ish. You are then using Math.floor which means it returns numbers 0 to 9. Then adding usrNum1 to it, gives a number between 4 and 13 (not 10).

Math.random() * (usrNum2 + 1 - usrNum1) would return between 0.0 and 6.9 -> 0 to 6 with Math.floor(). Then adding the num1 would make this from 4 to 10.

usrNum1 = 4;
userNum2 = 10;
var randNum = Math.floor(Math.random() * (usrNum2+1-usrNum1)) + usrNum1;

I think this does the trick. Cheers.

Bianca Power
Bianca Power
8,094 Points
Bianca Power
Bianca Power
8,094 Points

Great, that makes sense! Thanks so much!

Ethan M
Ethan M
10,637 Points
Ethan M
Ethan M
10,637 Points

Definitely a great method Bianca! I did something a lot different that Dave's solution. Everyone has a different way of doing things.

I did something very similar to your code but took a lot of trial and error for a beginner like me. I have had experience with JavaScript but I still suck at it haha. As well with C# but that's what programming is. Trial and error.

Good luck on your learning career and I am sure you will even find cooler ways on making the random number challenge!

Ethan M
Ethan M
10,637 Points

Also, Dave goes into incredible detail with his solutions for the learning purpose. It's so students really understand the purpose of the code.