Sometimes I have these moods or kicks where I decide that I want pure minimalism at the game table: one rulebook (or no rulebook), no screen, no mat, no miniatures, and the smallest possible number of dice.
Right now, I seem to be in one of those moods. It occurs to me that I could probably get away with running a game of D&D with just a d6, a d8, and a d20, and still feel pretty comfortable—and moreover, rolling all three dice at once, you can get a result for any common die size except for the d%.
I'll give you an example: I've just dug up some dice and rolled them, and I've turned up a 3 on d6, a 5 on the d8, and a 16 on the d20. This is actually every die roll from d2 through d20!
d2: Read the d6; if it's low (1–3), 1; if it's high (4–6), 2. I rolled a 1.
d3: Read the d6; some folks like the 1–2 = 1, 3–4 = 2, 5–6 = 3 method, and this "halve and round up" method does indeed seem to be the popular standard; but I find it easier to read the low range as it lies and subtract 3 from the high range—so in my case, I'd say I've rolled a 3 on the d3.
d4: Same as above, but for the d8: read it as it lies in the low range, subtract 4 in the high range. I got a 1 on the d4 (5 − 4 = 1).
d5: Read the ones digit off the d20 and subtract 5 if it's in the high (6–10) range: I got a 1 on the d5 (16 is read as 6, and 6 − 5 = 1).
d6: Read as it lies, 3.
d8: Read as it lies, 5.
d10: Read the ones digit as it lies, counting zero as ten: I got a 6.
d12: Read the d6 and count the d8 as a control die (1–4 means +0, 5–8 means +6); I rolled a 9.
d16: Read the d8 and count the d6 as a control die (1–3 means +0, 4–6 means +8): I rolled a 5.
d20: Read as it lies, 16.
This could be extended to a d24 using the d8 as the base roll and the d6 as a three-way control die, and similarly to a d30 with the d20 (read as d10) for the base roll and again d6 for a three-way control die; but d% requires rolling the d20 twice.
Anyway, just a bit of fun. I might have to try this out at my next game session!