Tsitsit-

Tsitsit are a Mitzva from the Torah. There are many opinions on which to tie them. Most Sephardim follow Maran HaChid"a, and wear a 10-5-6-5[Yud-Keh-Vav-Keh]. Bnei Yemen usually wear Ramba"m 3-3-3-3-3-3-3-(3)-(3)-(3)-(3)-(3)-(3)[39-Yud-Keh-Vav-Keh is one]. The Beni Ashkenaz usually wear a 7-8-11-13 according to Maran, but just one by one. Bnei Chabad usually wear Ari"zl, and wear 7(3,3,1), 8(2,3,3), 11(3,3,3.2), 13(1,3,3,3,3)[Took the opinion of Shulchan Aruch, and Rambam, and combined them equaling-Yud-Keh-Vav-Keh Echad]. Most Poskim agree that there should be 5 knots one reason-1)Corresponding to the 5 crowns(Some Kabbalah thing, I don't know it fully). 2)ציצית in Gimatria(Numerical Value) equals 600+the 8 strings(4 into half through one hole. Two holes according to the Ariz"l)+5 knots=613. Corresponding to the 613 Mitzvot. There is a Machloket(Disagreement) in the Mishnah whether you put 4, or 3 stings. Beit Shamai-4, and Beit Hilel-3. This is one out of the 18 time we follow Beit Shamay. You may not put more than 4 strings, and you may not put less.