The word abjad means chronogram, which is a mode of reckoning numbers by means of the Arabic letters of the alphabets, counting alif for one; bay for two; jim for three, etc. It may be noted that in English, only seven letters have of this chronogram, viz. C for 100, D for 500, I for 1, L for 50, M for 1000, V for 5 and X for 10.
It is said that the words of this chronogram, viz. Abjad, Hawwaz, Hutti, Kaliman, Saghaz, Qarshat, Sakhiz and Azzigh were the names of the eight sons of the inventor of Arabic characters, Muramier bin Murra. The lexicon Qamus writes that the first six are the names of the celebrated kings of Madain and the Arabs added the last two.
The names of an arithmetical arrangement of the Arabic alphabets, the letters of which have different powers from one to one thousand. The following is a list of the letter with the power of each in number:-
Alif = 1 yeh = 10 kaf = 100
bay = 2 kaf = 20 r'e = 200
jim = 3 lam = 30 shin = 300
dal = 4 mim = 40 te = 400
hay = 5 nun = 50 sa'y = 500
waw = 6 sin = 60 kh'y = 600
z = 7 ain = 70 zaal = 700
ha'i = 8 fay = 80 zwad = 800
to'i = 9 swad = 90 zo'i = 900
ga'in = 1000
Thus, the Arabs used to give each letter of the Arabic alphabet a numerical value as above. The 28 characters are divided into three successive series of nine each as under:-
from alif to to'i, the units (1 to 9)
from yeh to swad, the ten (10 to 90)
from kaf to zo'i, the hundred (100 to 900), and
ga'in is the equivalent of 1000.