Gary Gygax quote from Page 3 of Module B2
"When dice are used to randomly determine a number, the
type of dice used are abbreviated ‘d#’ (‘d4’ means a foursided
die, ‘d6’ a six-sided, and so forth). If more than one is
rolled, the number required is placed before the ‘d’ (‘2d6’
means two six-sided dice). If any number is to be added to
the total of the dice, it is indicated afterward (‘d4 + 2’ means
to roll a four-sided die and add 2 to the total: ‘2d8 + 1’ will
thus give a number from 3 to 17). You will quickly get to
know all of these abbreviations, and may use them when
you design your own dungeon."