Hey, love your youtube channel! All your talk of being a dice nerd has me wondering though, is it possible to use d6 dice as a d216? And if so, is this covered in your Goblin Guide? A forum post I found somewhere said it was definitely possible, but they used a big math formula a bit above my math level, which still counted for an Impossible for me since I couldn't break it down into roll number, adding or multiplying, etc.
Okay, so yes, it is very possible. Unfortunately, there is no "easy way" to do it. I don't know what formula you found, but I'm pretty sure the simplest would be.
1d6 + [(1d6 − 1] × 6) + [(1d6 − 1] × 36)
Which basically gives you three dice with the following values
Die 1: 1 2 3 4 5 6
Die 2: 0 6 12 18 24 30
Die 3: 0 36 72 108 144 180
Which provides a range of 1 [ 1 + 0 + 0 ] to 216 [ 6 + 30 + 180 ]
If you understand that you can stop reading now, the rest is just explanation of why that works.
To make it more clear what's going on we can also subtract 1 from the first d6, giving the following range
Die 1: 0 1 2 3 4 5
Die 2: 0 6 12 18 24 30
Die 3: 0 36 72 108 144 180
The range provided is now 0–215, and also essentially a d100 in base-6 read in base-10
if we look at the outcomes in order, D1 can return any number 0–5, then incrementing by 1 sets D1 back to 0 and D2 to 6. Then from there incrementing D1 gives you 6–11, at which point you once again set D1 back to 0 and increment D2 to 12. Similarly, when the D1 and D2 reach 35, incrementing by one sets them both back to 0 and increments D3 to 36. And if you're noticing that this sounds a lot like how binary works, yes, it is exactly the same except with 6 instead of 2—which makes it "senary." And then of course putting that 1 back onto the first die simply shifts the entire range by 1, from 0–215 to 1–216.
And basically, that is how to roll any value of X × Y, 1dX + [(1dY − 1] × X). and just for a little further example, let's look at a d18 rolled with 1d6 + [(1d3 − 1] × 6). Which gives the following values
Die 1: 1 2 3 4 5 6
Die 2: 0 6 12
Even though the dice are different, the math still works exactly the same.
And if you crave more dice maths, check out The Goblin Guide to Advanced Dice Rolling! The only dice math book you'll ever need... unless you get like into really complex maths.
