It is a mitzvah to recite Kaddish after every learning session. If verses of Scripture are learned, Kaddish Yehei Shelama is recited. Following rabbinic study, Kaddish d’Rabbanan is recited. It is customary that after rabbinic study, words of aggadah are added, for they please the heart, and consequently, the Kaddish recited afterwards is said out of happiness (Birkei Yosef 55:1; and see Mishnah Berurah 55:9). Therefore, after Pitum HaKetoret, further words of aggadah are added about one who learns halachot every day and about talmidei chachamim who increase peace in the world.
Some maintain that Kaddish is not to be recited unless ten people learn together, be it verses of Scripture or Chazal’s teachings (Aruch HaShulchan 55:5). Others say that even when two people learn together, and immediately upon their conclusion ten men assemble there, they may recite Kaddish on their learning (Magen Avraham; Mishnah Berurah 54:9 and 55:2). The custom is that one who wishes to recite Kaddish after his learning says aloud, “Rabbi Chananya son of Akashya says, HaKadosh Baruch Hu wanted to grant Israel merit, therefore He gave them the Torah and mitzvot in abundance,” etc. Since ten people hear these rabbinic words, they are considered to have learned, and then all opinions agree that Kaddish may be recited. Similarly, when saying Kaddish upon the recital of verses of Scripture, the person saying it should first say three verses aloud, and afterwards he may recite Kaddish according to all opinions.
