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

sebbe12
sebbe12
4,015 Points
Posted by sebbe12
sebbe12
4,015 Points

var a = Math.floor(Math.random() * (number1-number2+1))+number2;

How does this one work. Let's say number1 is 15 and number2 is 10.

This is my logic:

First it calculate (number1-number2+1))+number2; (15-10+1)+10 =16.

Then it takes 16 * Math.random() = Lets say Math.random is 0.05 then it should be 0.8 and result in 0.

How come everything land between 10-15.

1 Answer

Wikus van der Westhuizen
PLUS
Wikus van der Westhuizen
Courses Plus Student 4,335 Points
Wikus van der Westhuizen
Wikus van der Westhuizen
Courses Plus Student 4,335 Points

This is a basic math problem. You need to remember the order of computation: BODMAS

var a = Math.floor(Math.random() * (number1-number2+1))+number2;

Your oder of computation will be:

var z = (number1-number2+1);
var y = Math.random() * z;
var x = Math.floor(y);
var a = x + number2;

So using your example the computation will be:

var number1 = 15;
var number2 = 10;
var rndNumber = 0.05; // Substituting Math.random() with a fixed number

Math.floor(rndNumber * (number1-number2+1))+number2;
Math.floor(0.05 * (15-10+1))+10;
Math.floor(0.05 * (6))+10;
Math.floor(0.3)+10;
0 + 10;
10