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

Euan Burton
Euan Burton
3,037 Points
Posted by Euan Burton
Euan Burton
3,037 Points

Using math.random and Math.floor or Math.ceil for 6-sided die roll behaviour.

First I am really liking Dave's videos. In this last one we were making a program to display a six-sided dieroll.

I have one question with regard to the logic about using;

" var dieRoll = Math.floor( Math.random() * 6) +1; "

vs

"var dieRoll = Math.ceil( Math.random() * 6) ; "

As explained by Dave, there is a small chance that the math.random would return a 0, and math.ceil of 0 is 0, therefore the die roll could sometimes return a zero result.

But isn't the same logic true for the floor method sometimes returning a 1, and therefore this code could potentially execute to 7?

Cheers,

Euan

1 Answer

Shawn Flanigan
PLUS
Shawn Flanigan
Courses Plus Student 15,815 Points
Shawn Flanigan
Shawn Flanigan
Courses Plus Student 15,815 Points

Euan,

Good question, but Math.random() will never return 1. The closest it can get is something like 0.9999999999999999.

Euan Burton
Euan Burton
3,037 Points
Euan Burton
Euan Burton
3,037 Points

ok great!

Im not a math expert, but i'm guessing that the reason for that is that the having it return a value of 0-1, including both 0 and 1, would be infinitesimally greater than the width of one full integer. Makes sense. thanks a lot!