The Shulhan Aruch, in the Orah Haim section (46), codifies the obligation to recite a minimum of one hundred Berachot each day. Several different sources have been suggested for this requirement. The Talmud and the Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204) cite the verse in the Book of Debarim (10:12), "Ma Hashem Elokecha Sho’el Me’imach" ("What is it that Hashem your God demands of you"), which may also be read as, "Me’a Hashem Elokecha Sho’el Me’imach" – "Hashem your God demands one hundred of you." This verse thus alludes to the requirement to recite a blessing to God one hundred times each day.
Others point to the episode of the deadly plague that struck Beneh Yisrael during the reign of King David, killing one hundred people each day. In order to combat this plague, David instituted that every person should recite one hundred Berachot a day; sure enough, this practice was effective in bringing an end to the tragedy. Some have found an allusion to David’s enactment in a verse in the Book of Shemuel II (23:1), in which David refers to himself as the man "Hukam Al" – "appointed high." The numerical value of the word "Al" is one hundred, perhaps alluding to the daily recitation of one hundred blessings that David instituted. Yet another possible source is the verse in Tehillim (128:4), "Ki Chen Yeborach Gaber" – "Such shall a man be blessed." The words "Ki Chen" have the combined numerical value of one hundred, and thus the verse may be read as, "A person shall bless one hundred."
On weekdays, it is generally not too difficult to reach a total of one hundred Berachot. The three Amida prayers already comprise fifty-seven Berachot, and we also recite numerous Berachot as part of the morning prayer service, not to mention the Berachot recited before and after eating, after using the restroom, and so on. On Shabbat, however, the Amida consists of only seven Berachot, and so even with the additional Musaf prayer, the Amida prayers provide only twenty-eight Berachot. It is therefore advisable on Shabbat to eat snacks in between meals, in order to recite more Berachot. Additionally, some authorities maintain that one can have in mind while listening to the Berachot recited over the Torah reading that they should count toward his daily recitation of one hundred Berachot. Many also have the practice of smelling spices on Shabbat in order to add Berachot.
Hacham Ovadia Yosef rules that the "day" begins for the purposes of this Halacha only after the recitation of the Arbit service. Hence, the Berachot recited during Arbit count toward the previous day, rather than the following day. Accordingly, the Berachot recited during Birkat Ha’mazon after the Se’uda Shelishit meal on Shabbat count toward the Berachot of Shabbat, even if the meal extends past nightfall. Since Arbit is not recited until after Se’uda Shelishit, all the Berachot recited in the framework of Se’uda Shelishit count toward the Berachot of Shabbat.
The authorities debate the question of whether this obligation applies to women. The Shebet Ha’levi (Rabbi Shemuel Wosner, Bnei-Brak, contemporary) ruled that women are in fact exempt from this obligation. He suggests drawing proof to this position from the fact that the Bet Yosef (work by Maran, author of the Shulhan Aruch), in listing the daily Berachot that may be counted toward the total of one hundred, includes the Berachot recited over the Tallit and Tefilin, which women quite obviously do not recite. Hacham Ovadia Yosef, however, disagrees, and maintains that both men and women are required to recite one hundred Berachot each day. This poses quite a challenge for women, as our custom is that women pray only one Amida a day, and do not recite the Berachot of Pesukeh De’zimra and Keri’at Shema. Women should therefore endeavor to put themselves in a position to recite Berachot over the course of the day in order to fulfill this obligation.
In conclusion, it is worth emphasizing the unique power of Berachot, as reflected in the aforementioned episode of the deadly plague in the time of King David. That David responded by enacting the recitation of Berachot indicates that the proper recitation of Berachot has the capacity to save the Jewish people from calamity. It thus behooves us to not only ensure to observe this Halacha and recite one hundred Berachot each day, but also make a point to recite at least some of these Berachot with the proper concentration and feeling, in an effort to help protect Am Yisrael.
Summary: Halacha requires both men and women to recite one hundred Berachot each day, starting after the evening Arbit service.
