When one counts a group of Jews to determine how many they are, he should do so indirectly. This Halacha is inferred from the Torah law of "Mahasit Ha'shekel," which requires that when a census of the nation is taken, this should be done by having every member donate a half-shekel, and this money is then counted to determine the number of people in Beneh Yisrael. The Torah warns, "Ve'lo Yiheyeh Bahem Negef Bi'fkod Otam" – counting directly could lead to a plague, Heaven forbid (Shemot 30:12). The commentaries explain that counting directly invites the "Ayin Ha'ra" ("evil eye"), and thus poses danger. This applies even when counting for the purpose of a Misva. Therefore, when one counts the men present in the synagogue to determine whether they comprise a Minyan, he should not count directly, saying, "One, two, three" and so on. Some people mistakenly think that it suffices to count people while saying, "Not one, "Not two," "Not three," and so on. This is incorrect, as saying "Not one" is no different from simply saying "one." The two commonly accepted methods for counting people are to either count silently in one's mind, without saying the numbers, or to use a verse consisting of ten words and count each person by saying a word from the verse. One such verse is "Hoshi'a Et Amecha U'barech Et Nahaletecha, U're'em Ve'nas'em Ad Ha'olam" (Tehillim 28:9). Hacham Baruch Ben-Haim would use the verse, "Masmi'ah Hasir La'behema Ve'eseb La'abodat Ha'adam, Le'hosi Lehem Min Ha'aretz" (Tehillim 104:14). Others use the blessing of Ha'mosi, which consists of ten words ("Baruch Ata Hashem Elokenu Melech Ha'olam Ha'mosi Lehem Min Ha'aretz"). The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Mi'kabse'el (Parashat Vayehi), writes that the custom in Baghdad was to use a bead bracelet to count the people in the synagogue, separating one bead for each man in attendance.