There are lots of occasions in Warhammer 40,000 when you have to roll dice to see how the actions of your troops turn out – how effective their shooting is, what damage they've done to a vehicle, how far they fall back from enemy fire and so on. All of the dice rolls in Warhammer 40,000 use a standard six-sided dice (usually shortened to 'D6'). Sometimes you may have to modify the result of the dice roll. This is noted as D6 plus or minus a number, such as D6+1 or D6-2. Roll the dice and add or subtract the number to or from the score to get the final result. For example, D6+2 means roll a dice and add 2 to the score, giving a total of between 3 and 8.
You may also be told to roll a number of dice in one go, which is written as 2D6, 3D6 and so on. Roll the indicated number of dice and add the scores together, so a 2D6 roll is two dice rolled and added together for a score of between 2-12, 3D6 adds together the scores of three dice for a total of 3-18 and so on. For example, a 2D6 roll of a 5 and a 3 are added together to score 8. Another method sometimes used is to multiply the score of a dice by a certain amount. Therefore, D6x5 means roll a D6 and multiply it by 5, giving a total between 5-30.
Sometimes a combination of these methods may be used, such as 2D6+5 giving a score of between 7 and 17, or 3D6-3 which will total 0-15.
In very rare circumstances you may be told to roll a D3. Since there's no such thing as a three-sided dice, use the following method for determining a score between 1 and 3. Roll a D6 and halve the score, rounding up. Thus 1 or 2=1, 3 or 4=2 and 5 or 6=3.