VBM Different Ways to Divide the Plagues By Harav Yaakov Medan

Five and Five The ten plagues can be divided into two sets of five plagues each, in the same way that the midrash divided the Ten Commandments on the two luchot into two equal groups. Accordingly, the division is as follows: 1) Blood, frogs, lice, wild animals, and pestilence; 2) Boils, hail, locusts, darkness, and the plague of the firstborn. Indeed, we find a similar division in the Pesach Haggada, which compares the plague of the firstborn to pestilence: "With a mighty hand" (Devarim 21:8) – This is pestilence, as it is stated: "Behold, the hand of the Lord is upon your cattle which are in the field" (Shemot 9:3)… "And with an outstretched arm" (Devarim 26:8) – This is the sword [the plague of the firstborns], as it is stated: "With a drawn sword in his hand stretched out over Jerusalem" (I Divrei Ha-Yamim 21:16)