Don’t ask me what you need to hit. Just roll the die and I will let you know.

Tavis Allison and Cyclopeatron are musing about whether or not to reveal the target numbers for successful melee attacks to their players.

Dave Arneson has an oft-quoted saying: "Don’t ask me what you need to hit. Just roll the die and I will let you know." Essentially, Dave was advocating for keeping as much of the game mechanics off-stage as possible, thus allowing the players to immerse themselves in their characters and the world, rather than meta-gaming, or tailoring their play to the game mechanics.

While I concur with Dave's approach, and have been a vocal proponent of keeping much of the in-game mechanics behind the DM screen, both Tavis and Cyclopeatron make compelling arguments for (sometimes) revealing the to-hit numbers to the players.

The attached 'Percentage Index' table has been sitting on my computer desktop for several months. I think I came across it in one of my visits to the Original Dungeons and Dragons discussion boards. It seems rather Arnesian: rumor has it that, before the d10 and d20 became widely available, probability tables were constructed using the available dice-of-the-day, d6's. The above table allows you to calculate a d20/percentage probability from a throw of 2d6.

Dave Arneson was reportedly a fan of percentage systems. In my mind, I imagine this probability table hanging from Dave Arneson's DM screen, via a paper-clip, and, after calculating the percentage chance to hit, Dave peers over his screen and is saying, "Don’t ask me what you need to hit. Just roll the die and I will let you know."