Weekly Question Archive Index

1. What do the months of *Iyar* and *Tishrei* have in common?

2. On which day of the week do Hebrew months most frequently begin?

3. On which day of the week does *Rosh Chodesh* most frequently begin?

4. According to *Talmudic* tradition, which high officers were barred from the
*Sod Haibbur?*

5. In any given Hebrew year, what is the largest number of Hebrew months whose
first day can coincide with the first day of their corresponding Gregorian
month?

6. What is the next Hebrew year in which 3 Hebrew months will all start on the
first day of their corresponding Gregorian months?

7. What would be the very rare feature shared in common between the Hebrew
years 5774H (2013g/2014g) and 5676H (1915g/1916g)?

8. Does the first *Rosh Hashannah* of a longest possible 120 Hebrew year period
always begin on Thursday?

9. As measured from the first day of *Tishrei*, are all of the longest periods
of 120 Hebrew years exactly 98 Hebrew years apart?

10. In which year or years of the 19 year Hebrew calendar cycle is
*Rosh Hashannah* most likely to advance by another day in the Gregorian
calendar?

11. In which year or years of the 19 year Hebrew calendar cycle is
*Rosh Hashannah* most likely to occur at its earliest point in the
Gregorian year?

12. What is the repetition cycle of the moladot?

13. After the *molad of Tevet* 29,340H when next will *BaHaRaD* occur?

14. At least what 3 calendar features do the years 5758H (1997/8g) and
5759H (1998/9g) have in common?

15. What is the significance of September 16th to the Hebrew calendar?

16. How does September 16th fit into the leap and non-leap year separation pattern?

17. If your Hebrew calendar does not tell you the year length, is it possible
to determine that length without doing any arithmetic?

18. In the foreseeable future, will there ever be a Gregorian year without
a *Rosh Hashannah?*

19. In the foreseable future can 2 consecutive *Rosh Hashannot* ever begin in the
same Gregorian year?

20. In the foreseeable future, can 2 Gregorian years ever see the same
*Rosh Hashannah*?

21. Assuming the fixed calendar rules, could the Exodus have taken place
on a Thursday, in either the years 2448H or 2449H?

22. In the full Hebrew calendar cycle, how often do 19 year cycles of 6,942 days
occur?

23. When will, or did, occur the first 19 year cycle of 6,942 days?

24. When will, or did, occur the *third* 19 year cycle of 6,942 days?

25. Will the fourth of the longest possible 19 year cycles also begin on
Saturday?

26. Do all of the 295 longest possible 19 year cycles begin on Saturday?

27. How often does the reading of *Parshah Vayyeshev* coincide with *Shabbat Hanukah*?

28. What is the present difference between the time of the *molad* and the
corresponding mean lunar conjunction?

29. Approximately when will the Gregorian year value be the same as the Hebrew
year value?

30. What was the Hebrew acronym given to this once used leap year distribution

3 5 8 11 14 16 19 ?

31. How was the Hebrew leap year distribution of 3 5 8 11 14 16 19 different
than the currently used distribution of 3 6 8 11 14 17 19?

32. Assuming 13 Hebrew years, what is the oldest that a *bar/bat mitzvah*
celebrant can be on their 13th birthday?

33. Will the Gregorian 21st century begin on January 1, 2000g?

34. When will the next millenium start in the *Hebrew* calendar?

35. When will the next Hebrew non-leap year begin on September 17 after the
year 2240g?

36. In days, how long can be any period or cycle of 247 Hebrew years?

37. When did the least frequently occurring 247 Hebrew year period last begin?

38. What's the smallest number of consecutive Hebrew years that cannot add up to
a whole number of weeks?

39. When did, or will, occur the first of the shortest consecutive 8 Hebrew year
periods?

40. Since the period of the *molad* is less than 30 days, is it possible for the
*molad* to occur beyond the 30th day of a Hebrew month?

41. [Relative to year 5760H] When was the most recent occurrence of a *molad* on the 31st day of its preceding month?

42. [Relative to year 5760H] When will be the next occurrence of a *molad* on the 31st day of its preceding month?

43. Are the Albiruni *Rosh Hodesh* tables as shown in the Sachau translation
free of numeric typographical error?

44. How much more accurate than the traditional 29d 12h 793p was Albiruni's
stated value for the period of the *molad*?

45. Does the first day of *Iyar* always occur on the same day of the week as the
first day of the following *Rosh Hashannah*?

46. Which postponement rule governs the first day of *Rosh Hashannah* following a
Hebrew leap year whose *molad of Tishrei* is 4d 20h 500p?

47. In the full Hebrew calendar cycle of 689472 years, how many days are observed
as *Rosh Hodesh*?

48. Do the regular leap years of 384 days occur at least once in all of the
Hebrew calendar's 19 year cycles?

49. What is the most recent 19 year cycle in which no 384 day year can be found?

50. Besides the 384 day years, which other year length(s) might not be found
in all of the Hebrew calendar's 36,288 19-year cycles?

51. How often do Hebrew years of 383 days go missing from all of the 19 year
cycles in the full Hebrew calendar cycle?

52. Are all *Rosh Hashannah*'s separated by 247 years exactly one day apart in
their Gregorian calendar equivalents?

53. After *Rosh Hashannah* 5764H (*Shabbat* 27 September 2003g) when again will 4 out of 5 consecutive *Rosh Hashannah*'s begin on *Shabbat*?

54. After *Rosh Hashannah* 5764H (*Shabbat* 27 September 2003g) when will
4 out of 5 consecutive *Rosh Hashannah*'s begin on the same day other than
*Shabbat*?

55. After *Rosh Hashannah* 5775H (Thu 25 Sep 2014g) when next will 4 out of 5
*Rosh Hashannah*'s begin on the same day?

56. Do the numbers *2 4 7 10 12 15 18* constitute a valid leap year distribution
for the calculation of the Hebrew calendar?

57. The Encyclopedia Judaica, in its article on the ** Calendar**
cites the following leap year distributions as having been used

2 5 7 10 13 16 18 1 4 6 9 12 15 17 3 5 8 11 14 16 19 3 6 8 11 14 17 19

Additionally, the EJ suggests that the following values were used at one time
as the epochal *moladot*

4d 20h 408p 2d 5h 204p 6d 14h 0p 3d 22h 876p

Is the EJ entirely correct?

58. Which Hebrew year could most reasonably be represented as an
*epochal* year with the presence of the *molad* 4d 20h 408p?

59. Which Hebrew month least frequently has the *molad* of **0d 0h 0p**?

60. Is the Hebrew 5760H a leap year because it begins on the Gregorian date of
September 11?

61. When did all *Rosh Hashannah*'s beginning on September 11 first become
the start of ** ONLY** Hebrew leap years?

62. Can the time of a

63. Is it nececessary that

64.

What are at least 2 other Hebrew calendar phenomenae that will take place in the year 5760H?

65. When next will 5 consecutive Hebrew years have 4

66. [Nearest to 5760H] When will 4 out of 5 consecutive

67. In the full Hebrew calendar cycle of 689472 years, which

68. In the full Hebrew calendar cycle of 689472 years, how often do the

69. What fraction of the

70. How does Silberman's Paradox fail to disprove the fact that

71. Which *molad of Tishrei* is the second to be repeated in the full Hebrew
calendar cycle of 689472 years?

72. Is Al-Biruni correct in stating that 2 deficient years cannot follow
each other because *"the perfect months among the months of the cycle
(Enneadecateris) preponderate over the imperfect ones*"?

73.Can this table be used to calculate the *Tishrei moladot*?

1 | 5d 21h 589p |

2 | 3d 6h 385p |

3 | 0d 15h 181p |

4 | 6d 12h 770p |

5 | 3d 21h 566p |

6 | 2d 19h 75p |

7 | 0d 3h 951p |

8 | 4d 12h 747p |

9 | 3d 10h 256p |

10 | 0d 19h 52p |

11 | 5d 3h 928p |

12 | 4d 1h 437p |

13 | 1d 10h 233p |

14 | 5d 19h 29p |

15 | 4d 16h 618p |

16 | 2d 1h 414p |

17 | 0d 22h 1003p |

18 | 5d 7h 799p |

19 | 2d 16h 595p |

74. Using the table in Question 73, how can the calculations be extended to
more than 19 years?

75. How often are both *parshiyot Vayyeshev* and *Miketz* read on
*Hanukah*?

76. Which year, or years, of the *mahzor katan* (19 year cycle) cannot begin
a 19 year period of 6,942 days?

77. Measured from the 1st day of *Tishrei*, on which day, or days, of the week
can the longest period of 19 years begin?

78. Measured from the first day of *Tishrei*, which year, or years, of
the *mahzor qatan* (19 year cycle) can begin a 19 year period of
6,938 days?

79. Measured from the 1st day of *Tishrei*, on which day, or days, of the week
can the shortest period of 19 years begin?

80. Which is the first *molad of Tishrei* not to have appeared prior to the
repetition of the *Tishrei moladot*?

81. *Tu B'Shevat* cannot occur on which day, or days, of the week?

82. What is the frequency of occurrence of each of the Hebrew calendar's
different 19 year period lengths?

83. Which year, or years, of the 19 year cycle __most frequently__ begin(s)
the 6,938 day span of a 19 year period?

84. What, today, is the value of the year of the *Aera Alexandri*?

85. In the Hebrew calendar, what is the proportion of 29 day months to 30 day
months?

86. For the full Hebrew calendar cycle of 689472 years, is it possible to show
mathematically the actual proportion of 29 day months to 30 day months?

87. Using statistics relevant only to the 19 year periods, is it possible to
find the proportion of 29 day months to 30 day months?

88. On what day will both the Hebrew and Gregorian calendars first show the
exact same year?

89. On what day will both the Hebrew and Gregorian calendars first end the
exact same year?

90. What do *Shabbat, Monday, and Wednesday* have in common?

91. ** Weekly Question 91** is no longer available.

92. Which will be the last day to have the same year value in both the Hebrew and the Gregorian calendar?

93. [Relative to 5760H] When next will the

94. Which day, or days, of

95. Presently, what is the latest arrival time of the

96. When did the

97. Why is it impossible for a 385 day year to start on Tuesday?

98. What correction, or corrections, can be applied to Larry Padwa's response to

99. In which year, and for which month, will the value of the

100. In the

101. When next will *Rosh Hashannah* begin on a new Gregorian date?

102. After *Elul* 5760H, which starts on Friday 1 September 2000g, when next will
the *first* day of a Hebrew month coincide with the *first* day of
a __ Gregorian__ calendar month?

103. What does the coming Hebrew year 5761H (Mon 30 Sep 2000g) have in common with the year in which the Gregorian calendar was introduced?

104. Which calendar months are

105. What are the traditionally held correspondences of the biblically named months to the months in our present Hebrew calendar?

106. The Hebrew letters which form the name

107. [Referring to the end of question 106] Can you mention at least 3 other calendar related features of the Hebrew year 5761H?

108. Without any of the

109. Why does the Hebrew calendar postponement rule

110. For any possible period of Hebrew years, what are the possible number of Hebrew leap years within that period of time?

111. How often is *Sedrah Vayyelech* only partially read during the
course of a given Hebrew year?

112. Why does the longest possible period of 120 Hebrew years always begin on
Thursday?

113. Can the analysis of the answer to ** Weekly Question 112**
be used to explain the start of the longest and shortest possible
19 year periods?

114. How can the analysis of

115. What do the Tishrei moladot of the 11th, 13th, and 15th years of the

116. In the full Hebrew calendar cycle of 689472 years, how often will a molad of Tishrei be repeated if it is not for either the 11th, 13th, or 15th years of the

117.

118. For any period of

119. What is the minimum period of Hebrew years that can have the

120. What is the only date in the Hebrew Calendar that is sometimes celebrated as a holiday (with Hallel added to the service), and sometimes as an ordinary day (with Tachanun included in the service).

121. Do the longest periods of 10 Hebrew years always begin on Monday?

122. Do the * shortest* periods of 10 Hebrew years always

123. In eliminating the 356 day year, what unforeseen problem would have arisen if the period of the

124. Why is the 357 day Hebrew year impossible in the fixed Hebrew calendar?

125. Can

126. When will be the earliest coincidence of

127. When was the most recent coincidence of

128. When will be the next coincidence of

129. Can the

130. Why does adding 6 hours to the

131.Does the fast of the **17th day of Tammuz** occur most often
on a

132. How often are the

133. [Relative to the year 5760H] When was the most recent separate readings of

134. Can the

135. Other than

136. Why do the longest spans of 120 Hebrew years begin and end with abundant leap years starting on Thursday?

137. Which biblical coincidence involves 137 years?

138. At least which

139. When last did the first day of

140. When

141. Which is the shortest span of Hebrew years whose lengths in days give
all of the possible remainders after division by 7?

142. Which *unique* property is most likely common to spans of Hebrew years
whose lengths in days give all of the possible remainders after division by 7?

143. Which is the smallest span of years consisting of all of the possible
single year lengths?

144. For the 6 year spans which contain 6 different single year lengths,
in how many different ways can the single years be arranged over the full
Hebrew calendar cycle of 689,472 years?

145. What is the largest possible number of consecutive Hebrew years which
do not include all of the single Hebrew year lengths?

146. Are all 43 year periods missing a 384 day year preceded by 6 year periods
containing all six possible year lengths?

147. How many different arrangements are possible for the years in the
longest 43 Hebrew year spans excluding at least one single year length?

148. Is it possible to calculate the length of a single Hebrew year using no more than the postponement rule *Lo ADU Rosh*?

149. In order to always determine the length of a single Hebrew year, what would
be the *obvious* steps needed in the algorithm shown on pages 91-92
of the book * Calendrical Calculations* by Nachum Dershowitz and
Edward Reingold?

150. What was the highly significant Hebrew calendar event that took place on

151. What is, or are, the most significant common features of Hebrew years 264928H, 461920H, and 658912H?

152. Why are 352 day years not possible in the fixed Hebrew calendar?

153. Are people who become 32,896 days old on their Hebrew birthday born in a 12 month or a 13 month Hebrew year?

154. Which periods of Hebrew years beginning with 13 month years end with 13 month years?

155. What would be the *dehiyot* (Hebrew calendar postponement rules) were *Dehiyah Molad Zaqen* applied only to the *Tishrei moladot* that immediately follow Hebrew leap years?

156. What additional problem, or problems, might have be solved when *Dehiyah Molad Zaqen* is applied as suggested in *Weekly Question 155*?

157. In our times, is March 28 the earliest possible date for *Pesach*?

158. In changing the *Dehiyah Molad Zaqen* limit, what could Aaron ben Meir also have done to produce the same dates for *Rosh Hashannah*, as found in the currently fixed Hebrew calendar?

159. Absent *Dehiyah Molad Zaqen*, when next will a *molad* occur on the 2nd day of a Hebrew month?

160. Is *Birkat HaHamah* (the blessing of the sun) always said in the Hebrew month of *Nisan*?

161. When next will *Birkat HaHamah* (the blessing of the sun) not be recited in the Hebrew month of *Nisan*?

162. Which day, or days, of the week would have begun 356 and 382 day years had Friday been the only day disallowed for 1 *Tishrei*?

163. Which day, or days, of the week would have begun 356 and 382 day years had *Tuesday*, *Thursday*, and *Shabbat* been disallowed for 1 *Tishrei*?

164. What would have been the single year lengths had *Shabbat* been the
only day allowed to start *Rosh Hashannah*?

165. What is the smallest number of weekday combinations needed in order to view all of the possible *single year* statistical distributions when up to 6 weekdays may be disallowed for 1 *Tishrei*?

166. Why is it easy to count mentally the days from *Rosh Hashannah* 5663H to *Rosh Hashannah* 5763H?

167. When next, at *Rosh Hashannah*, will a 100th Hebrew anniversary be exactly 36,500 days long?

168. To get the greatest number possible of year lengths, which days of the week would have to be forbidden for 1 *Tishrei*?

169. To get the shortest possible 13 month year length, which day, or days, of the week would have to be forbidden for 1 *Tishrei*?

170. To generate the shortest possible year length, which day, or days, of the week would have to be forbidden for 1 *Tishrei*?

171. Is Hebrew year 5763H a 13 month year because it begins on *Shabbat* 7 September 2002g?

172. The next Hebrew year will be Hebrew year **5763H** beginning on ** Shabbat 7 September 2002g**. This year will be

173. What would be the lengths possible for periods of 19 Hebrew years if 356 and 382 day years were allowed in the Hebrew calendar?

174. When next will

175. In how many unique ways are the single year lengths arranged in the

176. By what fraction of the lunar month does the 12 month Hebrew year deviate from the traditional mean solar year?

177. Relative to the Hebrew calendar, what makes the year 5860H particularly interesting?

178. What makes year 5766H interesting in terms of the Hebrew calendar?

179. Up to now, how many

180. After 5343H (1582/3g), when next will a 420 Hebrew year period have 5,194 months?

181. In what proportion does any long and short period of *H* Hebrew years occur over the full Hebrew calendar cycle of **689,472 years**?

182. How frequently does *Rosh Hodesh* occur on *Shabbat*?

183. In any given Hebrew year, how frequently does *Rosh Hodesh* occur on *Shabbat*?

184. Which Hebrew year or years begin the shorter periods of H Hebrew years?

185. In days, what was the length of year 4596H?

186. From the Hebrew calendar perspective, what do the months of June and July 2003g have in common?

187. [Relative to year 2003g] when last did the first day of Sivan coincide with the first day of the Gregorian month of June?

188. [Relative to June 2003g] When last did a calculated *molad* result in a time prior to its announcement on *Shabbat*?

189. Which are two of the most important arithmetical properties of the 17th year of the *mahzor qatan* (19 year cycle) known as *GUChADZaT*?

190. What is the second major arithmetic property of the 17th year of the *mahzor qatan* (19 year cycle) known as *GUChADZaT*?

191. In any period of HY Hebrew years, what are the *minimum* and *maximum* number of months?

192. Which are two of the most important arithmetical properties of the 9th year of the *mahzor qatan* (19 year cycle) known as *GUChADZaT*?

193. What is the second major arithmetic property of the **9th year of the mahzor qatan (19 year cycle) known as GUChADZaT**?

194. How often is

195. What is an unusual feature of Hebrew year 5764H?

196. What effect, or effects, would be realized if postponement to Tuesday occurred whenever the

197. What major change, or changes, if any, would have to be made to the Gauss

198. What minimum

199. In how many ways can 7 leap years be distributed in 19 year cycles, such that the 13-month years have between each other either one or two 12-month years?

200. Of the 57 arrangements given in answer to

201. Is the leap year distribution known as *GUChADZaT* an astronomical or arithmetical derivation?

202. Which are the fundamental arithmetic rules governing the leap year distribution known as *GUChADZaT*?

203. Of what significance is *Tuesday* to *Hanukah*?

204. How many leap years would have been in the *mahzor qatan* if 240 lunar months had equalled 19 solar years?

205. On average, about how many years does it take for the Hebrew calendar to drift by one full lunar month?

206. In the Gauss *Pesach* formula, which year will first produce *zero* for the March offset?

207. For the Gauss *Pesach* formula, what would be the simplest way to avoid a *zero* March offset as early as year 9877H (6117j)?

208. In what year will the *molad of Nisan* be on *Sunday* at 17h 107p, as shown in chapter 6:7 of Mamonides' * Hilkhot Qiddush HaHodesh*?

209. What would have happened to the Hebrew calendar if at least 2 consecutive weekdays had been specified as postponement (

210. When again, in the next 1000 years, will the 30th day of

211. Which 2 reasons make 357-day years impossible in the currently fixed Hebrew calendar?

212. Which rule in the Babylonian *Talmud* eliminates the possibility of a 357-day year?

213. Which rule in the Babylonian *Talmud* eliminates the possibility of a 357-day year?

214. Assuming *Tishrei* 1 postponements of not more than 6 days, what is the length of the *smallest* Hebrew year that could then be generated?

215. Assuming the postponements of 1 *Tishrei*, what are the minimum number of days of postponement required in order to generate 350-day years?

216. Would any combination of at least 4 week days forbidden to 1 *Tishrei* lead to 350-day years?

217. What is the length of the Hebrew to Julian calendar correspondence cycle?

218. Why is *Pesach* so late in April 2005?

219. Which year, or years, of the *mahzor qatan* (19 year cycle) would have the earliest starting dates in a solar calendar?

220. Beginning from any year HY, what is the number of 12-month years that can be found within a given number of years ?

221. In exact fraction of year, how much longer is the Hebrew year over the Gregorian year?

222. Exactly how many years are required for a one year difference between the number of Hebrew and Julian years?

223. ** Hebrew Year 5765H** began on

Can you mention at least 3 other calendar related features of Hebrew year 5765H?

224. [Relative to 5765H] When next will there be a

225. [Relative to 5765H] When next will the

226. The whole hour

227. The whole day

228. How are the significant days of

229. What is the smallest possible span of Hebrew years to contain all 14 of the

230. The shortest spans of Hebrew years containing all of the 14

231. How many different sequences of *qeviyyot* can be found for the shortest spans of Hebrew years containing all of the 14 *qeviyyot*?

232. In the full Hebrew calendar cycle of 689,472 years, how many of the *GUChADZaT mahzor qatan*'s (19-year cycles) contain all of the 14 *qeviyyot*?

233. What is the smallest number of consecutive Hebrew years needed to ensure the presence of all of the 14 *qeviyyot*?

234. In up to 71 consecutive Hebrew years, what is the largest possible number of arrangements of their *qeviyyot*?

235. In how many possible combinations can be found the *qeviyyot* in Hebrew 32-year spans containing 13 *qeviyyot*?

236. Relative to 5765H, which one of the combinations of 13 *qeviyyot* in 32-year spans was most recently started?

237. What is the largest sequence of Hebrew years which does not contain all of the possible Hebrew year lengths?

238. In how many ways are arranged the year lengths found in 43-year spans containing exactly 5 different year lengths?

239. * World-wide*, and over the full Hebrew calendar cycle of 689,472 years, how often is read the weekly

240. Relative to

241. On which day of the Hebrew calendar did Christopher Columbus first sail for the Americas?

242. On which day of the Hebrew calendar did Christopher Columbus first set foot in the Americas?

243. Assuming that *Tishrei* 1 could be postponed from 1 up to 6 days from the day of the *molad of Tishrei*, what then would be the length in days of the longest single Hebrew year?

244. Assuming that *Tishrei* 1 could be postponed from 1 up to 6 days from the day of the *molad of Tishrei*, what then would be the length in days of the longest 12-month Hebrew year?

245. Assuming that *Tishrei* 1 could be postponed from 1 up to 6 days from the day of the *molad of Tishrei*, what then would be the length in days of the shortest 12-month Hebrew year?

246. Relative to 5766H (in 2005g), when last was *Dehiyyah B'TU'TKPT* invoked?

247. Relative to 5766H (in 2005g), when next will *Dehiyyah B'TU'TKPT* be invoked?

248. How far apart can be two consecutive invocations of *Dehiyyah B'TU'TKPT*?

249. Between which pair of Hebrew years does each of the possible 5 *B'TU'TKPT* separations first occur?

250. What are at least 3 other calendar oriented features relevant to Hebrew year 5766H?

First Paged 5 Nov 2004 Next Revised 18 Dec 2005