Is there a convention for prefixes for 10^n where abs(n) > 3 and n % 3 != 0? It seems strange to me that we would have prefixes for 10^+/-1 and 10^+/-2 but not for any larger values.
- decade
- century
- decagon
- centimeter
- decimal system
- decathlon
- centipede
edit: admittedly, hecto is pretty rare and centi is often used for both 1/100 and 100
> Centipedes (from New Latin centi-, "hundred", and Latin pes, pedis, "foot")
Hectolitres are commonly used in the food and drink industry. For example wineries and breweries typically measure their production in hectolitres.
Not exactly hecto but land, especially farm land is often measured in hectares. It is a non-SI metric unit equivalent to the square hectometer or 10000 square meters. We most likely kept the name because "hectare" sounds better than "square hectometer". As expected, 1 hectare is worth 100 ares, but ares and its other multiples are much less used than hectares.
2471 acres per hectare.
That may be in large part because of the unit prefixes we use. That is we think of these things in 3 orders of magnitudes because our unit prefixes come in three orders of magnitude but not the other way around. I think a much likelier explanation is the fact that many European languages (most importantly French and English) stop naming each decimal order after a thousand. If there was a word for ten-thousand—say fiorthom—but not a hundred-thousand (ten-fiorthom), surely these prefixes would map be multiples of 10⁴ as well.
... Or milliard, or giga
On paper, there are much larger units too, but they are never used.