In many Tabletop RPGs with dice resolution mechanics, there are numbers that we'll call target numbers. Depending on the system, they can be called any number of things: Difficulty class, To-hit, challenge rating etc. This number designates the number your player needs to roll (after adding appropriate bonuses) to succeed in any given task where the outcome is uncertain. 

You probably won't ask for a roll to open a door or climb a flight of stairs in normal circumstances because failure is unlikely, but also uninteresting. Similarly, you probably won't ask for a roll to survive after jumping off a cliff or to jump to the moon. It typically makes more sense to resolve action with slim-to-no chance of failure or success narratively and save the dice for rolls that are most likely to be interesting, success or fail. 

Let's talk about those rolls, and how they relate to the topic at hand. Your magic numbers describe 4 tiers of tasks:

• Menial tasks, potentially difficult for someone untrained or not an adventurer

• Average tasks, very difficult for the untrained and pedestrian. Most rolls should fall here.

• Difficult tasks, the untrained won't even  attempt; challenging most adventurers

• Heroic tasks, beyond fathoming for pedestrians, impossible for average adventurers on most days

Let's contextualize these a bit, shall we? Bear in the back of mind that the scale of these feats can be pushed forward or back depending on how superheroic or struggle-filled your adventure is intended to be. 

Menial 

• Crossing a river along slippery log

• Attacking a similarly skilled and sized enemy, 

• Wrestling a deer to the ground

• Recall common knowledge about a person, group, or historical event

• Convincing a guard to let you into a closed city, bribe in hand

Average

• Maintaining balance on that slippery log during combat

• Attacking an armored or  very skilled enemy. 

• Ascertain or recall a specific and convenient fact about a difficult or dangerous situation

• Stopping a charging bull without taking damage. 

• Bending rusted iron bars with a crowbar

• Convincing a merchant to lower his prices because you're buying in bulk now and provided details about the (imaginary) caravan that'll be buying from him every season starting next

Difficult Tasks

• Grabbing and restraining an armed opponent on a slippery log suspended over a river without being hurt in the attempt. 

• Attacking a very quick, armored goblin. Or an exceptionally armored and trained armored palace guard. 

• Tracking a lone individual from hours behind, in a blizzard

• Ten years ago, you read a book about this very specific building and can recall its layout and probable location of your party's goal

• Talking your way out of a highway robbery with a smile and flash of a sword

• Climbing a steep cliff with no aids and someone strapped to your back

Heroic Tasks

• Spinning this slippery log in such a way that neither you or your allies lose their balance as your opponents fall into the river

• Piercing the dragon's scales, between its own attacks, with a well-aimed blow

• Identifying number, type, and general location of several faraway targets by smell alone

• Convincing the Baroness to simply imprison your thieving friend, AND let the rest of you go, instead of executing the lot of you as initially planned. 

• "Climbing a slippery cliff one-handed, restraining a frenzied lion" - Kelsey Dionne 

In particularly well-designed game systems, these numbers will be laid out in a similar fashion near the front of the book. 

As a general rule:

D6 Systems:

Menial - Anything but a 1
Average - 3-4
Difficult - 5
Heroic - 6+

D20 Systems:

Menial - 9
Average - 12
Difficult - 15
Heroic - 18-22

Some time soon we'll put these numbers into practice and they should make more sense in context. For now, just keep in mind where these numbers are and what their names mean for your given system. 

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