Decillion

Decillion is a large number name used in formal mathematics and in written numerals. In the short scale, standard in American English and common in modern contexts, a decillion equals 10^33, i.e., a 1 followed by 33 zeros. In the long scale, once common in Europe and older British usage, a decillion equals 10^60 (a 1 followed by 60 zeros). The difference arises from distinct naming traditions in which each step represents a factor of 1,000 rather than 1,000,000.

The term is formed from the Latin decem meaning ten, together with the -illion suffix as in million, billion, and so on. The short-scale decillion sits three orders of magnitude above the million, whereas the long-scale decillion sits six orders of magnitude above the million.

In practical use, decillions are rarely encountered outside mathematical or speculative contexts. They appear in discussions of extremely large quantities, estimates in astronomy or physics, or in examples to illustrate scale. For reference, 2 decillions equals 2 × 10^33 in the short scale, while in older long-scale usage 1 decillion is 10^60 and 2 decillions is 2 × 10^60.

The adoption of the short scale for the term decillion has become standard in most English-language references; some European texts may retain the long-scale interpretation. Both definitions share the same morphological origin, differing only in scale.