I have been obsessed with dice as of late. I have been reverse engineering them to make a custom set. More on that later. Looking closely at my various d20's has yielded this:
The indica on this Gamescience specimen are placed relative to each other, so that the following are true: 1) the two matching numerals (in this case 8's) are on exact opposite sides. This means the other 8 is on the bottom. 2) If you look at all 9 faces which are up, they form a ring around the 8. No matter what you roll, if you imagine the dice as having an equator parallel to the table surface, all ten values 0-9 will be showing "up". This is built into the design of the die, who ever at Gamescience came up with this was a F-genius.
This is a Koplow (which I use a lot), notice the indica arrangement is not uniform as the Gamescience d20, above. Nice and hard, she is, but wacky.
This is what those kids are rolling these days when they are not playing their devil's music. This is marked 1-20. Bleh.
So here is the cool thing. As a crypt Lord, often you want to make rolls quickly to just determine stuff during play. With this method you can roll a % by making ONLY ONE ROLL. Listen:
Roll the die and draw an imaginary site line from your eyeball to the center of the up face (red line). The number it crosses MOST on this imaginary ring is the second number.
Like so. Remember all the other 9 numbers are in a ring around the top number...
...EXCEPT the other matching number (which is on the bottom). If you get a "liner", then double the number.
Another liner...this gives 100%. This kind of liner is a tougher one, but remember, you will be using these as shorthand rolls for mundane stuff. If it's life or death...make the a standard roll.
Does anyone remember how to roll-n-read a d20/0-9x2 any more? Kids these days.