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JavaScript JavaScript Basics (Retired) Working With Numbers Create a random number

Adam Maley
Adam Maley
5,946 Points
Posted by Adam Maley
Adam Maley
5,946 Points

Using Math.Ceil instead of Math.floor?

Math.floor(Math.random() * 6) + 1 How would this ever result in 0 like he said ?

the + 1 at the end would stop this from happening?

2 Answers

Tina Gee
Tina Gee
3,296 Points
Tina Gee
Tina Gee
3,296 Points

If you test Math.ceil() and Math.floor() in the console, it'll make a bit more sense.

For example, Math.ceil(-0.001) returns -0. Math.floor(-0.001) returns -1.

Since we are working with rolling dice and dice have sides 1 through 6 but never a 0 side, we will want to use Math.floor() because it will prevent us from having to deal with the possibility of Math.ceil returning a 0.

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

That's not quite right. Both Math.floor and Math.ceil could return a 0. But Math.floor gives you the same chances of getting each possible value.

Swedina Yolanda
Swedina Yolanda
931 Points
Swedina Yolanda
Swedina Yolanda
931 Points

It's said that Math.random returns a random number in the range from 0 up to 1, so I'm kinda confused with the -0.001 example.

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

You're right, Swedina, that's not an example of a value you could get from "Math.random". But it does illustrate the difference between "Math.ceil" and "Math.floor".

A better example might be the value "0.5".

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

It might result in 0 before the 1 was added.

Using Math.Ceil would not help the case where the value was actually zero.

I believe the possibility of the result of the formula being 0 was discussed as the reason to add 1 to it. If you heard otherwise, can you give a specific time reference in the video for where it is said?