Pinchas - Sh'vi'i
Shaking Things Up On Succos
Ah, but Succos... Now THAT's another story! Every day had a different musaf sacrifice.
On the first day: 13 bulls, 2 rams and 14 sheep, plus a goat for a sin offering.
On the second day: 12 bulls, 2 rams and 14 sheep, plus the goat.
The third day was the same, except that there were 11 bulls. On the fourth day, 10 bulls. The bulls decreased in number so that on the seventh day, seven bulls were offered. The total number of bulls offered over the week was 70, corresponding to the 70 nations of the world, on whose behalf these sacrifices were made. (See Talmud Succah 55b.)
On Shemini Atzeres, the korban musaf was one bull, one ram and seven sheep, plus the sin offering of a goat. (The one bull on Shemini Atzeres was for Israel - Talmud Succah 55b again.)
The different daily musaf offerings on Succos are the reason we say the full Hallel every day on Succos, but only on the first day of Pesach. The rule for Hallel is that it is only recited on days with a unique musaf offering. (See Talmud Arachin 10a-b.)