א 1 + ד 4 + ם 40 = 45. With the final mem at 600 (mispar gadol) it is 605.
Meaning
Adam is 'earthling', from adamah, the ground, and 45 is the number the tradition reads as the human being's own: it is also the Tetragrammaton filled with alephs (the MAH expansion, 45), so that 'adam' and the filled name are the same number. That identity is the Kabbalistic statement that the human is the name — the four letters written out at the scale of a person.