Random Tables, a How to

I really like to use random tables, but sometimes you find a resource that doesn’t match your dice evenly. This is a how to use a standard set of polyhedral dice for a selection from lists that were not made for random tables and do not divide easily.rawlins crest

While picking a random month of the year is easy to do with a d12 or the picking of a random element would take a four-sided die (assuming classical Aristotelian elements), the picking of a chapter at random when you have 39 chapters is less intuitive.

Three predominant techniques are used, often together to handle these odd-numbered lists. For this discussion I will assume the complement of four, six, eight, ten, twelve and twenty sided dice. The standard notation of d for dice followed by the maximum number on the die will be used, (meaning d4 for a four-sided die)

Technique the First: Reroll extras.

For a list of 5 items: wood, water, gold, fire  and earth how do you pick one at random without a d5. The answer is use a d6 but reroll every value over 5. This would work just as well for a d20 and reroll extra values, except for the need to reroll a lot more often.

Technique the Second: Roll multiple

Say you want to pick a random catch phrase from your favorite book for your character. The book has 100 chapters. Without a d100  you can roll a d10 and a d10, one being the tens place and the other the one’s place in the number.

Technique the Third: Modify rolls

Say you want to roll a number between 0-3. But most dice only roll between 1 and a number, you can add simple mathematics to alter the result. So for 0-3 you would roll a d4-1 and subtract that one. For a roll 1-3 you can do a d6/2. Division and multiplication really should only be used on lower number rolls to make them easy to mentally calculate.

And finally combine the three.

So for a chapter with 39 lines, roll a d4 and subtract one for the tens place and d10 for the ones place. Rerolling the d10 of 0 if the d4 is 4.

Or a bit more complex. For a chapter with 150 lines do a d6/2 to pick which set of 50, then a d6-1 (reroll 6) to pick a number 0-5 for the tens a d10 for the one’s place.

Sample Table

Say you have a cleric and you want to use some lines for the bible altered to fit your fantasy world lore.

Book Chapter Verse
17 Books Matthew has 28 chapters Chapter 28 has 20 verses
Roll 1d20, rerolling 18-20 roll a d30 and reroll 19-30, or roll a d6 for tens place and d10 for ones, divide the d6 result by two and if the combination is greater reroll it. roll a d20

This renders the verse below which can be molded and reused:

Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen. 

This gives me the quick statements for the cleric to use repeatedly; Teach them. He is always with you. To the End of the world.