How Many Zeros in a Duodecillion?
A duodecillion has 39 zeros: 1,000,000,000,000,000,000,000,000,000,000,000,000,000. In scientific notation, the zeros in a duodecillion are expressed as 1039. In the short-scale system used in the United States and modern United Kingdom, duodecillion follows undecillion (1036) and comes before tredecillion (1042). The prefix duo- means two, combined with dec- for ten — representing the twelfth group of three zeros beyond the ones place. In the long-scale system used in parts of continental Europe, a duodecillion instead means 1072, or 1 followed by 72 zeros. See also: Duovigintillion zeros.
A duodecillion has
39
zeros
- Written Form
- 1 followed by 39 zeros
- Scientific
- 10³⁹
What Is a Duodecillion, and How Many Zeros Does It Have?
A duodecillion is the number 1 followed by 39 zeros (1039). It is the 13th name in the short-scale "-illion" sequence, counting from million. To write it out in full: 1,000,000,000,000,000,000,000,000,000,000,000,000,000. See also: How many zeros in a nonillion.
The zero count is easy to verify: 39 = 3 × 13, meaning 13 groups of three zeros. Each group corresponds to one step up the naming ladder from million (1 group) through duodecillion (13 groups). The table below shows where it sits relative to its neighbors:
| Name | Zeros | Scientific Notation |
|---|---|---|
| Undecillion | 36 | 1036 |
| Duodecillion | 39 | 1039 |
| Tredecillion | 42 | 1042 |
The word is pronounced "doo-oh-deh-SILL-ee-on." While rarely used outside mathematics and reference contexts, duodecillion follows the same systematic Latin-prefix logic as every other "-illion" name in the sequence.
How Many Zeros Are in 10 Duodecillion?
Ten duodecillion (10,000,000,000,000,000,000,000,000,000,000,000,000,000) has 40 zeros. Any time you multiply an "-illion" by 10, you add one zero to the count. The same applies all the way up the scale: 100 duodecillion has 41 zeros, and 1,000 duodecillion — which equals one tredecillion — has 42 zeros. Related: Million zeros.
This relationship is directly reflected in scientific notation. One duodecillion = 1039; ten duodecillion = 1040; one hundred duodecillion = 1041. The exponent is always identical to the zero count, making scientific notation the most reliable way to track exactly how many zeros are in any large number.