Yoruba numerals

According to Lounge,^[1] the Yoruba language has a rather elaborate vigesimal (base-20) numeral system that involves both addition and subtraction and multiplication.

The base of the counting system is ogún 'twenty' (or 'score'). There are words for each of the decades; units in 1–4 are created by adding to these, while units in 5–9 are created by subtracting from the next decade. The odd decades are created by subtracting ten from the next even decade, as in Danish.

Up to 30, Yoruba has distinct forms of the numerals for counting objects, which derive from counting cowries.

	Numeral	Objects*	Tens**			Fives and tens			Hundred			Hundreds			Thousands			Myriads
1	ení, ọ̀kan	oókàn	11	ọ̀kanlá, oókànlá	10+1	25	ẹ́ẹdọ́gbọ̀n	30−5	110	àádọ́fà	20×6−10	210	ẹ̀walélúɡba	200+10	1400	egbèje	200×7	8,000	ẹgbàárin	2000×4
2	èjì	eéjì	12	èjìlá, eéjìlá	10+2	30	ọgbọ̀n, ọɡbọ̀n ǒ	–	120	ọ(gọ́)fà	20×6	300	ọ̀ọ́dúrún	400?−100	1600	ẹgbẹ̀jọ	200×8	9,000	ẹ̀ẹ́dẹ́ɡbàárùn	2000×5−1000
3	ẹ̀ta	ẹẹ́ta	13	ẹ̀talá, ẹẹ́talá	10+3	35	aárùndílogójì	20×2−5	130	àádóje	20×7−10	400	irinwó	4×?	1800	ẹgbẹ̀sàn	200×9	10,000	ẹgbàárùn	2000×5
4	ẹ̀rin	ẹẹ́rin	14	ẹ̀rinlá, ẹẹ́rìnlá	10+4	40	ogójì › ojì	20×2	140	o(gó)je	20×7	500	ọ̀ọ́dẹ́gbẹ̀ta › ẹ̀ẹ́dẹ́gbẹ̀ta	200×3−100	2,000	ẹgbẹ̀wá ~ ẹgbàá	200×10	16,000	ẹgbàájọ	2000×8
5	àrún	aárùn	15	ẹ́ẹdógún***	20−5	50	àádọ́ta	20×3−10	150	àádọ́jọ	20×8−10	600	ẹgbẹ̀ta	200×3	2,200	ẹgboókànlá	200×11	20,000	ẹgbàawǎ; ọkẹ́ kán	2,000×10; 1 bag
6	ẹ̀fà	ẹẹ́fà	16	ẹẹ́rìndílógún	20−4	60	ọgọ́ta › ọta	20×3	160	ọ(gọ́)jọ	20×8	700	ọ̀ọ́dẹ́gbẹ̀rin › ẹ̀ẹ́dẹ́gbẹ̀rin	200×4−100	3,000	ẹgbẹ́ẹdógún	200×15	100,000	ọkẹ́ marun	5 bags
7	èje	eéje	17	eétàdílógún	20−3	70	àádọ́rin	20×4−10	170	àádọ́sán	20×9−10	800	ẹgbẹ̀rin	200×4	4,000	ẹgbàajì	2,000×2	1,000,000	àádọ́ta ọkẹ́; ẹgbẹ̀ẹgbẹ̀rún	50 bags; 1000×1000
8	ẹ̀jọ	ẹẹ́jọ	18	eéjìdílógún	20−2	80	ọgọ́rin › ọrin	20×4	180	ọ(gọ́)sàn	20×9	900	ẹ̀ẹ́dẹ́gbẹ̀rún	200×5−100	5,000	ẹgbẹ́ẹdọ́gbọ̀n	200×25	2,000,000	ọgọ́rùn ọkẹ́, ọrún ọkẹ́	100 bags
9	ẹ̀sán	ẹẹ́sàn	19	oókàndílógún	20−1	90	àádọ́rùn	20×5−10	190	ẹ̀wadilúɡba	200−10	1000	ẹgbẹ̀rún	200×5	6,000	ẹgbàáta	2000×3
10	ẹ̀wá	ẹẹ́wàá	20	ogún, okòó	—	100	ọgọ́rùn › ọrún	20×5	200	igba, igbéo	—****	1200	ẹgbẹ̀fà	200×6	7,000	ẹ̀ẹ́dẹ́ɡbarin	2000×4−1000

* Oókàn is a contraction of owó ọ̀kan 'one cowrie'; 2–10, 20, and 30 are analogous.

** Lá is a contraction of lé ẹ̀wá 'and ten'.

*** Ẹ́ẹdógún is a contraction of aárùndí(n)(l)ogún 'five from twenty'.

*** igbéo is a contraction of igba owó 'a heap of cowries'.

Ogún is the basic word for twenty, okòó the word when counting objects. For thirty, the forms are ọgbọ̀n and ọɡbọ̀n ǒ. Units apart from the fives are generally transparent: oókànlélógún 'twenty-one', eéjìdínlọ́ɡbọ̀n 'twenty-eight', etc. There are also more recent decimal forms for the thousands: 2,000 ẹgbẹ̀rún méjì 'thousand twice', 3,000 ẹgbẹ̀rún mẹ́ta 'thousand thrice', etc., as well as additive forms for the fives, due to the influence of English. Numbers higher than 20,000 also tend to be transparent: 40,000 is ẹgbaawa lonan meji '20,000 two times'.

Notes

1. Lounge, 2009.

References

• Esiri, Ejiro. (2011). Numeral System of Yoruba: Focus on the Dialect of Oyo B.A Dissertation.
• Lounge, Olu. (2009). "A Vigesimal Number System".BookBuilders
• Lounge, Olu. (2009). "A Decimal Number System". BookBuilders