The gemorah in Menachos 43b tells us that someone should make at least 100 berachos everyday. Shulchan Aruch 46:3 brings this as the halacha. The reason is brought in the Be’er Hetev 46:6. One hundred people were dying per day. Dovid HaMelech decided to enact that everyone should say 100 berachos. With this enactment the plague stopped.
On a regular day of the week it is easy to reach this number. A problem though is presented on Shabbos. With each Shmoneh Esrai being 12 berachos shorter than during the week, 36 berachos are lost for the day. The best solution is suggested by the gemarah, that one should make berochas throughout Shabbos on smelling spices and eating fruit. A secondary solution is to have in mind, when hearing the berochos on Krias HaTorah and the Haftorah, to be yotzai. For this solution to work, the person making the beracha should have in mind to be motzi anyone listening. A lesser accepted solution is to do the same for the chazzans repetion of shmoneh esrai.

Rabbi Tzvi Aryeh HymanMir Yeshiva, Jerusalem- [email protected]