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. Multiples are also very important in the numerical system for example the number 60 is ọgọ́ta which literally means three twenties (ogún = 20, ẹ̀ta = 3).
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 | ẹ̀ẹ́dọ́gbọ̀n | 30-5 | 110 | àádọ́fà | 20×6−10 | 210 | ẹ̀wálélúɡba | 200+10 | 1400 | egbèje | 200×7 | 8,000 | ẹgbàarin | 2000×4 | |
| 2 | èjì | eéjì | 12 | èjìlá, eéjìlá | 10+2 | 30 | ọgbọ̀n, ọɡbọ̀n ǒ | – | 120 | ọ(gọ́)fà | 20×6 | 300 | ọ̀ọ́dúrún, ọ̀ọ́dúnrún | 400−100 | 1600 | ẹgbẹ̀jọ | 200×8 | 9,000 | ẹ̀ẹ́dẹ́ɡbàarùn-ún | 2000×5−1000 | |
| 3 | ẹ̀ta | ẹẹ́ta | 13 | ẹ̀tàlá, ẹẹ́tàlá | 10+3 | 35 | aárùn-ún-dínlógójì | 20×2-5 | 130 | àádóje | 20×7−10 | 400 | irinwó | — | 1800 | ẹgbẹ̀sán | 200×9 | 10,000 | ẹgbàarùn-ún | 2000×5 | |
| 4 | ẹ̀rin | ẹẹ́rin | 14 | ẹ̀rìnlá, 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 | ẹgbàajọ | 2000×8 | |
| 5 | àrún | aárùn-ún | 15 | ẹ̀ẹ́dógún*** | 20-5 | 50 | àádọ́ta | 20×3-10 | 150 | àádọ́jọ | 20×8−10 | 600 | ẹgbẹ̀ta | 200×3 | 2,200 | ẹgbọ̀kànlá | 200×11 | 20,000 | ẹgbàawàá; ọ̀kẹ́ kan | 2000×10; 1 bag | |
| 6 | ẹ̀fà | ẹẹ́fà | 16 | ẹ̀rìndínlógún, ẹẹ́rìndínlógún | 20-4 | 60 | ọgọ́ta › ọta | 20×3 | 160 | ọ(gọ́)jọ | 20×8 | 700 | ọ̀ọ́dẹ́gbẹ̀rin › ẹ̀ẹ́dẹ́gbẹ̀rin | 200×4−100 | 3,000 | ẹgbẹ̀ẹ́dógún; ẹ̀ẹ́dẹ́gbàajì | 200×15; 2000x2-1000 | 100,000 | ọ̀kẹ́ márùn-ún | 5 bags | |
| 7 | èje | eéje | 17 | ẹ̀tàdínlógún, ẹẹ́tàdínlógún | 20-3 | 70 | àádọ́rin | 20×4-10 | 170 | àádọ́sàn-án | 20×9−10 | 800 | ẹgbẹ̀rin | 200×4 | 4,000 | ẹgbàajì | 2000×2 | 1,000,000 | àádọ́ta ọkẹ́; ẹgbẹẹgbẹ̀rún | 50 bags; 1000×1000 | |
| 8 | ẹ̀jọ | ẹẹ́jọ | 18 | èjìdínlógún, eéjìdínlógún | 20-2 | 80 | ọgọ́rin › ọrin | 20×4 | 180 | ọ(gọ́)sàn-án | 20×9 | 900 | ẹ̀ẹ́dẹ́gbẹ̀rún | 200×5−100 | 5,000 | ẹgbẹ̀ẹ́dọ́gbọ̀n; ẹ̀ẹ́dẹ́gbàata | 200×25; 2000x3-1000 | 2,000,000 | ọgọ́rùn-ún ọ̀kẹ́, ọrún ọ̀kẹ́ | 100 bags | |
| 9 | ẹ̀sán | ẹẹ́sàn-án | 19 | ọ̀kàndínlógún, oókàndínlógún | 20-1 | 90 | àádọ́rùn-ún | 20×5−10 | 190 | ẹ̀wádínlúɡba, àádọ́wàá | 200−10 | 1000 | ẹgbẹ̀rún | 200×5 | 6,000 | ẹgbàata | 2000×3 | 3,000,000 | àádọ́jọ ọ̀kẹ́ | 150 bags | |
| 10 | ẹ̀wá | ẹẹ́wàá | 20 | ogún, okòó | — | 100 | ọgọ́rùn-ún › ọrún | 20×5 | 200 | igba, igbéo | 20x10 | 1200 | ẹgbẹ̀fà | 200×6 | 7,000 | ẹ̀ẹ́dẹ́ɡbàarin | 2000×4−1000 | 4,000,000 | igba ọ̀kẹ́ | 200 bags | |
* 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'.
*** Ẹ̀ẹ́dógún is a contraction of aárùn-ún-dí(n)(l)ógún '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 ẹgbàawàá lọ́nà méjì '20,000 two times'.