Dear Straight Dope:
Why do they call a thousand dollars a GRAND? I mean, I get the idea that it's a grand amount of money, but who started using the term? Where did it come from?
The term “grand” is American slang from the early 1900s, presumably from the expression “a grand sum of money” to mean $1,000. As with most questions of etymology, we don’t know who first used the phrase. The best we can do, in most cases, is to find the earliest written usage, which is around 1915 for “grand.” But the term was probably used in conversation for a while before it appeared in writing.
Within a few decades, the term was so popular that it was abbreviated to G or G-note. During WWII, the Yanks brought the term to the UK, where it came to mean £1,000.
By the late 1940s, a grand meant a thousand of almost anything, not just money. Grand old flag, however, and grandparents still retain the OTHER meanings of “grand,” just to confuse people for whom English is a second language.
Another term that refers to a thousand is a thou, which was first recorded in 1869, and is still in use. The derivation is obvious. A similar but not necessarily synonymous term is K, short for kilo, as in kilobyte. Kilo is the Greek prefix for thousand, so strictly speaking one might use “10K” to mean $10,000. What confuses matters is that in the world of computers K sometimes means not 1,000 but 210, or 1,024. A kilobyte of memory is 1,024 bytes, a megabyte is 1,024 times a kilobyte, and a gigabyte is 1,024 times a megabyte. However, when you get to computer network speeds, they tell me–I claim no personal expertise–that kilo (as in kilobits per second) = 1,000. Some try to keep things straight by using k to mean 1,000 while K means 1,024, but I venture to say most of the world is unaware of that distinction. To further confuse matters, in calculating hard disk capacity, some tech vendors say there are only 1,000 KB in a megabyte, not 1,024. (See faq.mrtg.org/FAQ024.html for more.) Save yourself some trouble and stick with grand.
BONUS INFO! You’ve heard of kilobytes, megabytes and gigabytes. Some of you may even have heard of terabytes, the next jump up from giga. Given the dizzying advance of technology, someday soon we’ll need prefixes for even larger quantities. What are they? Luckily, the big heads of science have been on the job. Here are the terms as agreed upon in 1990 (see www.danbbs.dk/~erikoest/quanti.htm for details):
|peta-||1000^5||1024^5 = 2^50 = 1,125,899,906,842,624|
|exa-||1000^6||1024^6 = 2^60 = 1,152,921,504,606,846,976|
|zetta-||1000^7||1024^7 = 2^70 = 1,180,591,620,717,411,303,424|
|yotta-||1000^8||1024^8 = 2^80 = 1,208,925,819,614,629,174,706,176|
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