Why do people keep saying 12 tribes of Israel when there are 13?

Question

The Encyclopædia Britannica article “Twelve Tribes of Israel” says (emphasis added),

Jacob’s first wife, Leah, bore him six sons: Reuben, Simeon, Levi, Judah, Issachar, and Zebulun. Each was the father of a tribe.

That’s six tribes.

The article continues,

Two other tribes, Gad and Asher, were named after sons born to Jacob and Zilpah, Leah’s maidservant. Two additional tribes, Dan and Naphtali, were named after sons of Jacob born of Bilhah, the maidservant of Rachel, Jacob’s second wife. Rachel bore Jacob two sons, Joseph and Benjamin.

That’s another six, to make a total of twelve.

But Joseph produces two tribes, Efraim and Manasheh. There is no tribe of Joseph.

So there are thirteen tribes in all.

Perhaps Levi doesn’t count due to its lack of territory. But the article clearly says that Levi is a tribe. And then it goes on pretending that there are twelve tribes all along.

Is my math correct?

This has been bothering me for years since childhood. Why does nobody seem to think there is any problem? Your math is correct the Levites were the priests however both sons Mannassah and Ephraim came from Joseph and because they were brothers counted as 2 tribe

Answer 1

Jacob had twelve sons, and on spiritual matters, we count those twelve. With Levi as one and Joseph as one. (That's for instance what you'd find on the High Priest's decision breastplate.)

On financial/land matters, however, Levi did his own thing, and Joseph got a double portion as his sons Ephraim and Menashe. For instance, there were spaces for twelve tribes forming a camp when they traveled in the desert -- Ephraim and Menashe each count as one -- but the Levites stayed inside of the ring of those twelve. Similarly when they got to Israel, a chunk of land was allocated to Ephraim, and another chunk to Menashe. The Levites just got scattered cities all over the land, with special rules.

So: on spiritual matters: yes Levi, and Joseph=1, total =12. On monetary matters: no Levi, and Joseph=2, total=12.

Answer 2

The Torah lists off the names of the tribes in multiple places. Every time, there are 12: either because Levi is counted, and Yosef is counted as one tribe, or because Levi is not counted, and in those cases Efraim and Menashe are both counted. Thus, we say '12' because that's clearly what the Torah is trying to do - emphasize that however you count the total should be 12

Answer 3

Your math is quite correct. Others have explained the details of how you get to twelve anyhow, in various different places in the Torah. In case you're also interested in why, there's a couple of Rambans:

שנים עשר מטות. מטה אהרן הוא בי"ב, כי לא אמר ותקח מטה לבית לוי ותכתוב עליו שם אהרן, אבל הוא במנין הנזכר, והנה לא נחשב יוסף רק לשבט אחד. והטעם, כי לא ימנו שבטי ישראל לעולם רק שנים עשר, ומפני שיחשוב לוי יחשוב יוסף רק אחד. ועוד אפרש זה בסדר וזאת הברכה (דברים לג ו) אם יברכני ה' להגיע לשם: This is because the tribes of Israel are always twelve, and since the tribe of Levi was counted among the twelve, Yosef had to be counted as only one tribe. I will explain more about this in seder V’zos Habracha if Hashem blesses me to reach there. [Numbers 17:17]

והנכון בעיני, כי הכתוב לא ימנה בשבטי ישראל רק שנים עשר, וכך אמר בברכת יעקב (בראשית מט כח) כל אלה שבטי ישראל שנים עשר. והנה יעקב הזכיר בניו השנים עשר והזכיר יוסף בשבט אחד, ומשה ראה להזכיר ביוסף שני שבטים כמו שאמר (פסוק יז) והם רבבות אפרים והם אלפי מנשה, והיה זה בעבור שני דברים, האחד כי אחר שצוה הקדוש ברוך הוא ועשאם שני שבטים בחנכת המזבח, ובדגלים, ובנחלת הארץ, הנה הוא צריך למנותם שנים בברכתם, ועוד שהזכיר יהושע המנחילם את הארץ והוא מאפרים הקטן והוצרך להזכיר אחיו שגדול ממנו והנה רצה לברך את לוי כי מברכתו יתברכו כל ישראל, שיהיו קרבנותיו לרצון להם לפני השם, והוצרך להשאיר אחד מן השבטים שאינן נימנין בשום מקום רק שנים עשר, כנגד שנים עשר מזלות ברקיע, ושנים עשר חדשים בשנה, ושנים עשר גבולי אלכסונין,
The correct explanation to me is that the Torah always counts the tribes of Israel as twelve, as in the blessings of Yaakov, These are the tribes of Israel, twelve. Behold, Yaakov counted his sons as twelve and mentioned Yosef as just one. Whereas Moshe wanted to count the sons of Yosef as two [for the following reasons...] And he wanted to count Levi [for the following reasons...] - therefore he needed to leave off one of the other tribes not to be counted. For never are the tribes anything but twelve, corresponding to the twelve constellations in the heavens, and the twelve months of the year, and the twelve diagonal directions... [Deuteronomy 33:6]

Fascinating and of course needs more explanation. But one of the hidden parts of the Torah.