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JavaScript

Posted by raquel pinto
raquel pinto
12,549 Points

Help ! I did the method, and ask a number between 4 and 6. And it gives me 4, or 6 inclusive.

var starting_input = prompt("Please, tell me a starting number");
var finish_input = prompt("Please, tell me a limit number");

var bottomNumber = parseInt(starting_input);
var topNumber = parseInt(finish_input);

var randomNumber = Math.floor(Math.random() * (topNumber - bottomNumber + 1)) + bottomNumber;
alert( randomNumber + " is a number between " + starting_input + " and " + finish_input);

Well, If I put 4 and 6 as my limits. I would like the answer to be 5 as an number between 4 and 6. But instead, the (Math.random() * (topNumber - bottomNumber + 1) gives a number between 0 and 2.99999. And with the math floor, gives an number between 0 a 2.

How can I make the range between 1 and 1.99999. So I can add the bottom number (4) and have the 5 as an answer ?

1 Answer

Steven Parker
Steven Parker
243,656 Points
Steven Parker
Steven Parker
243,656 Points

You just need to implement a different formula.

This is the formula for inclusive random ranges:

(random * (topNumber - bottomNumber + 1)) + bottomNumber

And this is the formula for exclusive random ranges:

(random * (topNumber - bottomNumber - 1)) + bottomNumber + 1
raquel pinto
raquel pinto
12,549 Points

Great!!! Thank you so much!