Midrash su II Cronache 14:8

(Exodus 14:7) "and shalishim upon all of them": "shalishim" are warriors, as in (Ezekiel 23:23) "shalishim and notables — all riders of horses." Variantly: "and shalishim upon all of them": They were "triple ("meshulashim") -armed. R. Shimon b. Gamliel says: This refers to the third (man in the chariot). In the past there were only two charioteers. Pharaoh added a third to pursue Israel the more swiftly. Rebbi says: There were three and Solomon added a fourth. Variantly: "and shalishim": Three (Egyptians) against every one (Israelite). Others say: three hundred against one. And how did Pharaoh know how many Israelites died in the three days of darkness and how many left Egypt? He took out their registries and apportioned warriors accordingly. Similarly, R. Yirmiyah expounded (II Chronicles 14:8) "And Zerach the Cushite went out against them with an army of a thousand thousands and three hundred chariots." How did he know how many there were of them? According to the number of (their) chariots, he apportioned warriors. Variantly: "and shalishim 'upon all of them'": ('al kulo') in order to destroy them. In the past (he commanded [Exodus 1:22]) "Every son that is born, into the Nile shall you throw him," but here, "and "shalishim 'al kulo'" ("in order to destroy" [all of them]), viz. (Ibid. 15:9) "I shall draw forth my sword; my hand shall impoverish (i.e., eradicate) them."