Hebrew numerology stems from a systematically applied set of numerical values assigned to the twenty-two letters of the Hebrew alef-bet.  These values display a base 10 logarithmic progression, thusly:

ק=100 י=010 א=001
ר=200 כ=020 ב=002
ש=300 ל=030 ג=003
ת=400 מ=040 ד=004
ך=500 נ=050 ה=005
ם=600 ס=060 ו=006
ן=700 ע=070 ז=007
ף=800 פ=080 ח=008
ץ=900 צ=090 ט=009

Another numerological method can be derived from the איק  בכר (Aiq Bekhar), a two-dimensional array which very well may be the ancient predecessor of the modern-day Pigpen Cipher:

ג ל ש ב כ ר א י ק
ו ס ם ה נ ך ד מ ת
ט צ ץ ח פ ף ז ע ן

This method aligns letters with each other based on an additive reduction of their digit values; letters in the first cell all have an additive numerological reduction value of 1 (1 = 1+0 = 1+0+0), letters in the second cell all have an additive numerological reduction value of 2 (2 = 2+0 = 2+0+0), and so on.  As one can see, the name of this scheme comes from the ordering of the first two cells (איק בכר).  The final letter forms of the five letters which possess them are also included, to fill out the grid, and they are consequently attributed numerological values as given in the first table above.  However, there is considerable doubt that the final letter form values existed in ancient times, when numerological values are thought to have originated, because the ancient letters had no such final forms.  Kaf (כ), Mem (מ), Nun (נ), Peh (פ), and Tzaddi (צ) always appeared the same when written in the ancient letter forms, regardless of whether located within or at the beginning or the end of a word.  Nonetheless, they are included here (alternately shaded) for the sake of those who need a reference for modern numerological schemes.

The use of numerology, or gematria, as it is known in Kabbalah, dictates that words or text forms (such as abbreviations, acronyms, etc.) sharing the same numerological value are somehow also related in a mystical sense.  Some words in Hebrew sharing the same numerological values seem to be ill-matched, but the nature of the relationship is not implied, but rather, only the notion that there is one.  One example of this can be found in the numerology of the Hebrew words אחד (Echad:  one) and בהו (Bohu:  waste; void).  Both of these words possess a gematriatic value of 13; however, they are understood to correspond to different (if not opposing) influences in kabbalistic theory.  Of course, words which have the same Hebrew spelling but different vowels/pronunciations will naturally share the same numerical value, such as מלך (Melekh:  king), and מלך (Molokh:  archdemon corresponding to the Qlifoth of Kether, and an ancient pagan Qena'anite idol), which both have a numerical value of 90.