How the Omer Magic Formula (G.S.S – 7) saved the vacation


If you were stranded on an island without a Jewish calendar and no internet connection (oy gevalt!), how would you know what number to count in the Omer?

Every year, on the second night of Passover, we begin a special 49-day period in the Jewish calendar known as Sefirat Ha’omer, the counting of the Omer.

Counting the Omer is a Biblical mitzvah, mentioned in Leviticus 23:15, and it is performed consecutively for 49 nights by reciting a blessing followed by the correct count of that particular night. On the first night – “Today is one day to the Omer”, on the second night – “Today is two days to the Omer” and so on, until the 49th night – which is always the night before Shavuot.

Rabbi Soloveitchik interprets this mitzvah as a sign that we control our own time – which is the mark of free people, while other commentators offer interesting and profound explanations for this mitzvah. The problem, however, is how to remember the correct count for any particular night, especially now that we’re past the first week. This Friday, for example, is it 14 or 15 or 16 to the Omer?

Sure, you can look up a Jewish calendar or go online and find websites, but what if you don’t have access to calendars or to the web? Imagine you are in an army operation where no electronics are allowed? Or what if you’re hiking on the Appalachian Trail?

Magic Formula: G.S.S – 7

Every year there is a magic formula to figure out the correct Omer count on any given night. It can be summarized with the acronym G.S.S – 7 which means:

  1. Guess a number
  2. SUBTRACT the day of the week (Sunday=1, Monday=2, etc).
  3. SUBTRACT magic number 1
  4. If your result is DIVISIBLE BY 7 (or it’s 0), your guess is right. If not – make another guess and repeat the process.

Let’s see how this formula saves the day by following the story of the Morgensterns who went on a vacation to Pago Pago Island.

Yaakov and Rachel Morgenstern felt they needed quality time together, and so they left all their smartphones and tablets back home, and traveled to the romantic island of Pago Pago. They arrived there on Friday April 17, and immediately relished the amazing landscape and inviting beaches of this American Samoa island.

Just before they sit down for a Shabbos meal, they remember that they haven’t counted the Omer. They are about to begin the blessing, but to their chagrin, they realize they have forgotten what’s the correct count. Because they were so excited about the trip – they can’t remember what’s the correct count tonight.

Both of them know the Halakhic rule that if you forget to count one night, it irreparably disrupts the count, and you are not allowed to continue counting the Omer with a blessing on any of the following nights. They are deeply concerned because they are about to lose the ability to perform this special mitzvah for the rest of the Omer season. This would ruin an otherwise magical vacation.

 Just when they think all is lost, Rachel remembers the magic formula. Excitedly, she exclaims: “Guess, subtract day, subtract magic number 1, divisible by 7?

She proceeds to make a reasonable guess. “Let’s try 15 for tonight’s Omer number. After all, we started counting about 2 weeks ago so it must be in this range.”
Applying the formula, from her guess of 15 she subtracts the day of the week, Friday:

15 – 6 = 9
She then subtracts magic number 1:

9 – 1 = 8

The result, 8, is not divisible by 7. That means her original guess is wrong. It cannot be that we count 15 tonight.

Catching on quickly, Yaakov understands they need to refine their original guess so he suggests “Let’s try 14 and see what happens.”

They reapply the magic formula:

14 – 6 – 1 = 7


The result, 7, is of course divisible by 7, showing that the refined guess of Omer count 14 is the correct count for this Friday night!

They did it! Without any connection to the outside world, our couple figured out that this Friday night, April 17, we count 14 in the Omer.

They high-five and drink a L’chayim, joyous that they were able to perform this mitzvah and count the Omer properly.

This formula will work for any night of the Omer this year, with a small caveat that your guess has to be within a range of 7 of the correct count. That should not be a problem because most people know the approximate range we’re in so their guess is not completely wild.

The formula is good for every year, but the magic number changes. In other words, the additional number to subtract after you subtract the day of the week – changes every year. But once you know the magic number, this formula will ensure that you’ll never forget the correct Omer count, even if you find yourself on the beautiful Seychelles Islands or the International Space Station.

Shamai Leibowitz is the operations and ritual director at Congregation Har Tzeon-Agudath Achim.

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