Editing Warhammer 40,000/7th Edition Tactics (section)

===Dice Roll Math===
*It is almost always better to re-roll dice than to get +1.  For instance, re-rollable 4+ has almost a 10% edge over 3+.
**The exception is re-rolling 6's, which is 1/36 worse than 5+.
**Because of how people throw dice, a re-rollable 2+ has a lower chance than math suggests. People tend to use the same rolling motions, which means those dice often end up in the same position ("1" both times).
*A scatter die has a 1/3 chance of rolling "hit", making it better than or equal to BS2.
**Despite being good for low-accuracy units, blasts also favour high BS units.  Up to BS7, you get increase RoI on accuracy.
**Against large targets, like tanks, a difference of 1-2" makes little difference.  However, *any* scatter usually costs hits against infantry.
*The average of 2d6 is 7.
**Average number of 3d6 is 10.5. 4d6 is 14. 
*Picking the highest of two dice adds about 1 (actually .9722....) to the average roll.
*4+ re-roll 5+ is the same as 3+.
*And, if you're into it, there's [[MathHammer]].
*GW dice are not mathematically fair! This set of mathematical data presumes you are using perfectly balanced casino dice which are. See following for details. http://www.dakkadakka.com/wiki/en/That%27s_How_I_Roll_-_A_Scientific_Analysis_of_Dice