Why not use *7 to scale the Math.random() number?

Can you tell me if I'm understanding this correctly?

Math.random() returns a floating point number between 0(included) and 1(excluded).

We're trying to get numbers between 1 and 6, like a die.

So, adding the *6 will scale that random number up by six (right?) For example, the highest random number would be something like .99999999999, and then *6 = 5.99999, and then when Math.floor is applied, it's rounded down to 5. Right?

So why do we add the +1? Why can't we just scale the random number up higher? Like *7?

I know I'm missing a chunk of understanding here, I'm just not sure what it is and my brain is being fuzzy.

I looked here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random to further understand how math.random functions, and I think we're dealing with this formula

// Returns a random integer between min (included) and max (included) // Using Math.round() will give you a non-uniform distribution! function getRandomIntInclusive(min, max) { return Math.floor(Math.random() * (max - min + 1)) + min; }

This looks like a way to generate numbers between and including two numbers, but how would I use that (max-min) part?

Thank you for your help.