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

Marleen Berg
Marleen Berg
22,524 Points
Posted by Marleen Berg
Marleen Berg
22,524 Points

I have a different solution, is this correct?

var minNumber = prompt("give your min number!");
var maxNumber = prompt("give your max number");

var diceRoll = Math.floor(Math.random() * parseInt(maxNumber) + parseInt(minNumber))+1;
alert(diceRoll);

I will have correct results, as far as I did test....

Adomas Domeika
Adomas Domeika
6,151 Points
Adomas Domeika
Adomas Domeika
6,151 Points

yep, looks like your code is correct.

Sorry. Changing my opinion, why? Because if you enter your max number 20 an min number 15, then if random generates 18, you add the min number and the answer is 33. Sorry for the wrong answer.

2 Answers

Alexander Davison
Alexander Davison
65,469 Points

I found a bug. I set minNumber to 5, and maxNumber to 11, and I got 15.

Hint on fixing bug: Sometimes, Math.random() * maxNumber can be close to maxNumber, because Math.random() can be close to 1, and if you add minNumber to that quantity, it may be above maxNumber.

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

The math being applied here is not correct for creating a random number that will be within the two limits entered. The formula shown here will give you a number with a minimum one higher than the lower value, and a maximum of the sum of the two numbers entered.

The correct formula for a within-range random number with even distribution is:

random * range + minimum

where "range" is :point_right: maximum - minimum + 1