How Many Candles?

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How many candles do we light on Chanukah? There are two ways to calculate this. One is to add up every number from 2 (1 + a shamash) through 9 (8 + a shamash) = 44. The other is to recognize that this is an arithmetic series and use the simple formula: 1/2 * n * (A1 + An) = 1/2 * 8 * (2 + 9) = 44.

Now calculate how many candles you would have to light if Chanukah was 15 days or 30 days (135 and 495).

Legend has it that the basis of this formula was figured out by an elementary school student named Carl Friedrich Gauss, when his teacher told the class to add up all the numbers from 1 to 100 and he was able to do it in a few seconds (more info: I, II).

R. Mordechai Marcus once told me that there is a Tosafos, I don’t remember where but perhaps in Bekhoros [Menachos 106a s.v. she-hein elef], that offers a similar formula.

(inspired by an e-mail from Dr. Yitzchak Levine)

About Gil Student

Rabbi Gil Student is the Editor of TorahMusings.com, a leading website on Orthodox Jewish scholarly subjects, and the Book Editor of the Orthodox Union’s Jewish Action magazine. He writes a popular column on issues of Jewish law and thought featured in newspapers and magazines, including The Jewish Link, The Jewish Echo and The Vues. In the past, he has served as the President of the small Jewish publisher Yashar Books and as the Managing Editor of OU Press. Rabbi Student has served two terms on the Executive Committee of the Rabbinical Council of America and currently serves as the Director of the Halacha Commission of the Rabbinical Alliance of America. He serves on the Editorial Boards of Jewish Action magazine, the Journal of Halacha and Contemporary Society and the Achieve Journal of Behavioral Health, Religion & Community, as well as the Board of OU Press. He has published five English books, the most recent titled Search Engine volume 2: Finding Meaning in Jewish Texts -- Jewish Leadership, and served as the American editor for Morasha Kehillat Yaakov: Essays in Honour of Chief Rabbi Lord Jonathan Sacks.

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