Yi / Oku (East Asian) (yi)
One hundred million (10⁸), written 億 / 亿 in Chinese and Japanese (oku) and Korean (eok). East Asian counting groups numbers by myriads.
1 yi / oku (East Asian) = 100,000,000 pieces (exactly).
About the yi / oku (East Asian)
Chinese counting does not group digits in threes. It groups them in fours, so 1,234,567,890 is read as 12 yi, 3456 wan, 7890. Wan is 10,000 and yi is 10,000 times wan, giving 100,000,000. In Japanese the same character is read oku and in Korean eok. The yi is therefore a pure number with no physical dimension, and its base here is simply one.
This myriad system differs from English, which builds on thousands. One million is 100 wan, and one billion in the short scale is 10 yi, since these languages have no native words for powers of one thousand. Ancient texts wrote 10,000 squared as wan wan before yi became the name. Older usage differed, and yi once stood for 10 to the 5th. The next unit, zhao, is 10 to the 12th in Taiwan, Japan and Korea, but mainland China has used it for a million, so official documents avoid it.
Sources: Wikipedia: Chinese numerals; Wikipedia: Myriad
Yi / Oku (East Asian) conversion chart
1 yi / oku (East Asian) expressed in every other counting & quantity unit:
| Unit | 1 yi / oku (East Asian) |
|---|---|
| Pieces | 100,000,000 |
| Dozens | 8,333,333.333 |
| Lakhs | 1,000 |
| Millions | 100 |
| Crores | 10 |
| Billions (short Scale) | 0.1 |
| Pairs | 50,000,000 |
| Hundred | 1,000,000 |
| Gross | 694,444.4444 |
| Thousand | 100,000 |
| Trillions (short Scale) | 0.0001 |
| Score | 5,000,000 |
| Half Dozens | 16,666,666.67 |
| Quadrillions | 1×10⁻⁷ |
| Reams | 200,000 |
| Moles | 1.660539067×10⁻¹⁶ |
| Baker's Dozens | 7,692,307.692 |
| Small Gross | 833,333.3333 |
| Great Gross | 57,870.37037 |
| Myriads | 10,000 |
| Arab (Indian) | 0.1 |
| Kharab (Indian) | 0.001 |
| Billions (long Scale) | 0.0001 |
| Quires | 4,000,000 |
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