Configuring the "Arba Parshiyos" Puzzle
It is well known that during the current “simchah season” known as the joyous month(s) of Adar, many changes were instituted to the normal weekly Torah readings, in the Maftir and Haftarah, each for their own purpose and reason.
First up is Parashas Shekalim, on the Shabbos before or of Rosh Chodosh Adar (Sheini), which commemorates the communal mitzvah of the giving the Machtzis HaShekel, used to pay for the daily Korban Tamid for the whole year.
Next is Parashas Zachor, which is always read on the Shabbos before Purim, as it evokes and condemns the unprovoked attacks of the evil Amalek on Klal Yisrael, paralleling and foreshadowing the genocidal plot of his wicked descendant, Haman, detailed in Megillas Esther, which is read on Purim.
Third is Parashas Parah, on the third week of Adar, commemorating the Parah Adumah (Red Heifer) used to purify Klal Yisrael for the upcoming Korban Pesach.
Lastly, on the Shabbos before or of Rosh Chodesh Nisan, is Parashas Hachodesh, to properly honor the coming of the “First Month” that we were commanded in the Torah to observe, Rosh Chodesh Nisan. These four changes to the Maftir and Haftarah are collectively known as the “Arba Parshiyos”.
The Gemara in Megillah (29a - 30b) devotes considerable attention to the details of the “Arba Parshiyos”, including how to compute the Jewish calendar’s nineteen-year-cycle of which exact week will host which special reading. It seems a bit confusing, but luckily several of our great early authorities, including the Rif, Rashi, and the Rosh, give a simple mnemonic that allows anyone to figure out which week is which. This is especially practical for a shul’s gabbai who has to arrange the Sifrei Torah to the proper places on each of these weeks. In fact, this code is so useful that it is even cited as halacha by the Tur and Shulchan Aruch.
ZAVD”U - זבד"ו - Unlocking the Code
In our Jewish calendar, the second day of Rosh Chodesh Adar, meaning the first actual day of Adar, can only fall out on four days of the week - Shabbos, Monday, Wednesday, and Friday. In a leap year, such as ours - 5779 - these calculations and configurations apply exclusively to Adar Sheini, as it is considered the main Adar for these inyanim.
This is due to the Gemara concluding that all Purim-related observances, including the Arba Parshiyos, are celebrated in Adar Sheini, in order that the Geulah from Haman on Purim and the Geulah from Egypt on Pesach, should be observed in consecutive months. In fact, the majority consensus is that if a boy was born in a non-leap year, one which there was only one Adar, and on the year of his Bar Mitzvah there are two Adars, his Bar Mitzvah will occur in the second Adar, since it is considered the true one.
Back to explaining the code. The mnemonic for these days that Rosh Chodesh Adar can occur on is ZAVD”U. This stands for Zayin, the seventh day of the week - Shabbos, Beis stands for the second day of the week - Monday, Dalet refers to the fourth day of the week - Wednesday, and Vav the sixth day of the week – Friday.
The Rishonim teach us that each of these letters stands for an additional code: ZAT”U, B”O, DA”D, U”BIV (or U”BYU); and knowing their meanings will help us calculate which week each of the Parshiyos will fall out on. The first letter of each of these codes refers to which day of the week Rosh Chodesh Adar falls out on, and the remaining letters refer to which day(s) of the week during the month is a “skip week”, with no special reading.
ZAT”U – ז"טו
ZAT”U refers to when Rosh Chodesh Adar falls out on a Shabbos (“Zayin”, the seventh day of the week), then that day itself - Shabbos (the first week), Parashas Shekalim is read, the subsequent Shabbos is Parashas Zachor, the next Shabbos - “TU” or the fifteenth of Adar - is a “skip week” with no exceptional attributes, the following Shabbos is Parashas Parah, and the last one is Parashas Hachodesh. This breakdown of the code applies for all the rest as well.
B”O – ב"ו
B”O refers to when Rosh Chodesh Adar falls out on a Monday (“Beis”, the second day of the week). Then, the preceding Shabbos is Parashas Shekalim, that week (with Shabbos being the sixth day of Adar - “O” or “Vav”) is a skip week, and the remaining weeks are all special reading weeks consecutively: Zachor, then Parah, and followed by Hachodesh.
DA”D – ד"ד
DA”D is similar to B”O, with Rosh Chodesh Adar falling out on a Wednesday (“Dalet”, the fourth day of the week), with Parashas Shekalim being the preceding week, that Shabbos (the fourth of Adar - “Dalet”) being a skip week, and all remaining weeks are consecutive special reading weeks as well.
U”BIV (or U”BYU) - וב"יו
U”BIV, (or U”BYU)is a bit more complicated, with two skip weeks. This occurs when Rosh Chodesh Adar falls out on Friday (“U” or “Vav”, the sixth day of the week). The preceding Shabbos is Parashas Shekalim and the day immediately following Rosh Chodesh (the second of Adar - “Beis”), which is Shabbos, is a skip week. The next week is Parashas Zachor, and the following (on the sixteenth of Adar - “IV”, “Yud-Vav”) is another skip week. The remaining subsequent weeks are Parah and Hachodesh, respectively.
One may realize that this is actually this year’s (5779 / 2019) Adar code, containing the two skip weeks. Hence, this year, it turns out that Parashas Vayakhel is Parashas Shekalim, Parashas Pekudei is a skip week, Vayikra is Parashas Zachor, Tzav, following on the heels of Purim, is a skip week, Shemini is Parashas Parah, and Tazria is Parashas Hachodesh.
The Gemara in Shabbos (75a) stresses the importance of knowing the calculations of our calendar, with many Rishonim understanding that there is a specific mitzvah to do so. The Chazon Ish explicitly mentions the calculations of the Lunar month as a prime example of this. Although for many, making calendarical calculations seems to be out of the realm of expertise, thankfully our great Rishonim have led the way, enabling even the layman to utilize Hashem’s tools to at least configure the Arba Parshiyos puzzle.
This article was written L’Iluy Nishmas R’ Chaim Baruch Yehuda ben Dovid Tzvi, L’Refuah Sheleimah for R’ Shlomo Yoel ben Chaya Leah, Shoshana Leah bas Dreiza Liba, Mordechai ben Sarah, and Shayna bas Feiga, and l’zechus Shira Yaffa bas Rochel Miriam v’chol yotzei chalatzeha for a yeshua sheleimah!
Rabbi Yehuda Spitz serves as the Sho’el U' Meishiv and Rosh Chabura of the Ohr Lagolah Halacha Kollel at Yeshivas Ohr Somayach in Yerushalayim. He also writes a contemporary halacha column titled ‘Insights Into Halacha’. For any questions, comments or for the full Mareh Mekomos / sources, please email the author: firstname.lastname@example.org.
 “Mishenichnas Adar Marbin B’Simchah” (Gemara Taanis 29a).
 See at length Gemara Megillah 29a - 30b. For a brief summary of the Gemara’s conclusion see Mishnah Berurah (685: 1).
 “Hachodesh Hazeh Lachem Rosh Chadashim, Rishon Hu Lachem Lechadshei Hashana” (Parashas Bo, Shemos Ch. 12: 2). Everyone knows the famous Rashi on the very first pasuk of the Torah citing Rabbi Yitzchak [see Sifsei Chachamim and the Taz’s Divrei Dovid ad loc. as to the identity of this Rabbi Yitzchak, whether Rashi’s father or the Amora; see also Bereishis Rabba Ch. 1: 2 and Midrash Tanchuma Hayashan, Bereishis 11], that the Torah could have started with this pasuk, as it was the very first Mitzvah given to Klal Yisrael as a nation.
 Our set calendar was established millennia ago by Hillel II.
 Rif (Megillah 10b), Rashi (Megillah 30b s.v. v’ee), Rosh (Megillah Ch. 4, 10, end s.v. Yerushalmi), Tur and Shulchan Aruch (Orach Chaim 685: 6).
 Gemara Megillah 6b. See also Terumas Hadeshen (vol. 1: 294).
 See Rema (Orach Chaim 55: 10; based on Shu”t Mahari Mintz 15), Levush (Orach Chaim 685: 1), Magen Avraham (Orach Chaim 55: 10), Pri Chodosh (ad loc. 10), Pri Megadim (ad loc. Eshel Avrohom 10), Levushei Srad (ad loc. s.v. eino), Korban Ha’eida (Yerushalmi Megillah Ch. 1, Shiyarei Hakorban s.v. hada), Shaarei Teshuvah (Orach Chaim 55: 11), Kitzur Shulchan Aruch (15: 2), Aruch Hashulchan (Orach Chaim 55: 14), Mishnah Berurah (ad loc. 45), and Kaf Hachaim (ad loc. 59); not like the Maharash Halevi (Shu”t Orach Chaim 16), who is of the opinion that Adar Sheini is only considered the true Adar for Purim related issues, exclusive of Bar Mitzvahs. However, this might not hold true for observing yahrtzeits, as this is a machlokes between the Shulchan Aruch and Rema (Orach Chaim 568: 7), as explained by the Mishnah Berurah (ad loc. 41), as to which Adar is ikar for this, with several authorities maintaining that it is preferable for a yahrtzeit to be observed in both Adars. See also Shu”t Igros Moshe (Yoreh Deah vol. 3: 160) who concludes that even regarding yahrtzeits the essential Adar is Adar Sheini. Other issues of dispute include Shtaros, Gittin, and Nedarim. This topic was elucidated at length in a previous article titled ‘Tale of Two Adars: Computations and Complications’.
 This is basic Gematria. Each of the letters of the Hebrew Aleph-Beis has an equivalent numerical value. For example, Aleph equals one, Beis equals two, Dalet equals four, Vav equals six, Zayin equals seven, etc. Hence, Beis, which equals two, refers to the second day of the week, Monday. Dalet, which equals four, refers to the fourth day of the week, Wednesday, etc.
 Except of course for those fortunate enough to live in Yerushalayim (or other walled cities from the time of Yehoshua Bin Nun), for that skip week is actually Purim Meshulash, a rare three-day Purim extravaganza, with the different mitzvos of Purim applying separately on Friday, Shabbos, and Sunday.
 This year, Metzorah then becomes Shabbos Hagadol, which is always the Shabbos immediately preceding Pesach, an honor which usually is reserved for Parashas Tzav (in a standard, non-leap year). According to the Abudraham (Seder HaParshiyos, pg. 372), and cited lemaaseh by the Levush (Orach Chaim 428: 4) and Elyah Rabbah (ad loc. 5), the reason why Parashas Tzav generally falls out on Shabbos Hagadol, is that it mentions the halachos of Kashering Keilim (Vayikra Ch. 6: 21), albeit regarding the Korban Chata’as, as ‘haga’alas keilim chometz lamud m’Korbanos’. Although in a leap year (such as ours) Parashas Metzora is usually read directly before Pesach, it is also in sync, as it mentions ‘kli cheres yishaver’, which is quite apropos for Pesach as well.
 They are divided though, whether it is a Mitzvah Deoraysa or Derabbanan. The BeHa”G (Mitzvos Kum Asei 75), SMa”G (Asein 47), SMa”K (Mitzva 103; however, he holds that this is part of the Mitzva of Kiddush HaChodesh) and the Sefer Yereim (Mitzvah 60), count this as a Mitzva Deoraysa, while the Rambam in his Sefer HaMitzvos (Shoresh HaRishon) and the Ramban (Hasagos ad loc.) write explicitly that they are are of the opinion that it is Derabbanan.
 The Chazon Ish (Orach Chaim 138: 4) writes that knowing the calculations for the Lunar month is considered Torah.See also Rav Chaim Kanievsky’s introduction to his Shekel HaKodesh, where he recounts the importance and reverence the Chazon Ish held of calculating the months, and how he even would consider his mathematical calculations as needing geniza. See Rav Yisroel Reisman’s excellent “Pathways of the Prophets” (pg. 272 – 311), who expounds upon and elucidates practical examples of understanding calendar calculations at length.
Disclaimer: This is not a comprehensive guide, rather a brief summary to raise awareness of the issues. In any real case one should ask a competent Halachic authority.
L'iluy Nishmas the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga, Rav Yaakov Yeshaya ben R' Boruch Yehuda.