In gematria, Mem represents the number 40 in both the Standard and Mispar Gadol Methods of Gematria; However, (mem sofit) final mem's value is 40 in the Standard Method and 600 in the Mispar Gadol method. The Standard Method adds the values of Tav and Resh (400+200) to denote the value of mem sofit.
In the Sefer Yetzirah, the letter Mem is King over Water, Formed Earth in the Universe, Cold in the Year, and the Belly in the Soul.
Mīm is used in the creation of ism words (i.e. nouns and adjectives; they are treated fundamentally the same in Arabic grammar). Specifically, mīm is used in the creation of the masdar (verbal noun) of Stem III verbs (the masdar of verbs on the pattern fā`ala is mufā`ala), of subject and object nouns for verbs of Stems II-X (using the example of Stem II, subject nouns — called fā`il words because of their form in Stem I — are mufa``il, and object nouns — called maf`ūl also because of their Stem I form — take the form mufa``al). Place-nouns are also created with mīm; the pattern maf`al is used to create maktab "office" from the triliteralk-t-b (to write) and maṣna` "factory" from ṣ-n-` (to make).