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JavaScript

Posted by Kristian Woods
Kristian Woods
23,414 Points

How does Math.floor(Math.random() * 6) + 1 work?

I'm trying to understand how this process works:

Math.floor(Math.random() * 6) + 1;

Process:

Math.random() creates a number between 0 - 0.9

The "*6" multiplies random number by 6 - This creates a number between 0 - 5

Example: 0.4 * 6 = 2.4

Math.floor() takes a decimal number and converts it into an integer 2.4 = 2

The +1 is then added to create a number between 1 - 6

If the random number is “0” - it adds 1 to make it 1. if the random number is 5 - it adds 1 to make it 6

Is this thinking correct?

Thanks

1 Answer

Jennifer Nordell
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STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

You're correct. And we can look at the two extremes to prove this. If Math.random() rolls a 0 we take that and multiply it by 0 which gives us 0. Then we floor it, which in this case has no effect. We still have 0. Then we add a 1. That gives us a total of 1.

If Math.random() were to roll 0.9, we take that and multiply it by 6 which gives us 5.4. Then we take the floor of that which is 5. Then we add 1 which gives us a final result of 6. So the random numbers will only ever be between 1 and 6.

Kristian Woods
Kristian Woods
23,414 Points

Thank you so much, Jennifer. You have cleared that up!