Ten Thousand Nanomegaquestions Quiz

Quiz Answer Key and Fun Facts

1. Computer storage has brought some prefixes into common knowledge that, a few years ago, only scientists would have been familiar with. Which of the following is the correct order for the next three prefixes after "Mega-", from smallest to largest?

Answer: Giga-, Tera- , Peta-

These three prefixes stand, respectively, for a factor of one thousand to the third, fourth and fifth power or, to use more standard scientific terminology, ten to the ninth, twelfth and fifteenth power. They are frequently used with the "Byte" unit to represent computer storage.

In the early 2010s, main memory is typically measured in Gigabytes (billions of bytes) while hard disks tend to have capacities in the Terabyte (trillions of bytes) range. Large data centers can often store several Petabytes (quadrillions of bytes) worth of information.

2. Larger prefixes than the one for a billion are loosely derived from Greek names for numbers, counting groups of three zeroes. Representing one quintillion or 10 to the 18th power, which prefix thus counts six such groups?

Answer: Exa-

Derived from "hexa", meaning "six", this prefix was until 1991 the largest SI prefix. It is occasionally heard in conjunction with the unit Watt as some researchers are working on lasers capable of delivering such an amount of power - one million times the output of the entire US power grid or six times the amount of radiation Earth receives from the Sun - for a very short pulse (less than one trillionth of a second).

By the way, "Tera-" is derived from "tetra" (four) and "Peta-" has its roots in "penta" (five).

3. Going one step further, we now look at 10 to the 21st power. Which prefix, again using the "count groups of three" pattern but this time closer to the Latin number name, stands for this mammoth multiplier?

Answer: Zetta-

After the previous pattern, one would have expected the "Epta-" prefix to coincide with Greek "hepta" for seven, but this would have caused a conflict with the abbreviation letter. Thus, the Latin "septem" was used as the root, simplified to "Zetta" in order to have the rare Z as the key letter instead of the S already used in many other meanings. One Zettameter is the approximate diameter of the Milky Way - one hundred thousand light years!

4. We have one more - eight groups of three zeroes make 10 to the 24th power. The Greek and Latin word "octa" and "octem" are almost the same, but the unit again adds a little individuality. Which is the correct prefix for this number?

Answer: Yotta-

Again, the first letter has been chosen simply to create a prefix that does not easily conflict with any commonly used units or digits ("O" in a unit symbol would cause serious confusion with the zero digit) while also keeping the pronunciation of the word simple and reminiscent of its root. One Yottagram of water - one quintillion metric tons - is a decent approximation for all oceans of the world (the true amount is about 40% higher). "Yotta-" has, after the 1991 extension of the scale, become the highest officially used SI prefix and retained that status well into the new millennium.

5. So far, we have only looked at powers of one thousand, but there are also the "deka-" and "hecto-" prefixes that multiply the base unit by 10 and 100 respectively. If I wanted to express 10 kilovolts (ten thousand Volts) via a phrase beginning with the word "one", which would be an SI-compliant way to do so?

Answer: One thousand dekavolts

Apart from the first two powers of ten, the SI system only has prefixes for the powers of one thousand. The "myria-" prefix for 10,000 was actually part of the original metric system published in 1795, but was never accepted into SI. Also there is no legal way to put two prefixes in front of a unit.

However, any number can be used with any prefix, so "one thousand dekavolts" and "one million centivolts" are confusing, but legal ways to refer to the 10 kV voltage.

6. Of course there are not only prefixes for very large quantities but also for tiny ones. Which of these is NOT an SI prefix used to denote a fraction of a unit?

Answer: itsi-

Just like the "Mega-" and "Giga-" prefixes have been derived from various words for "large", the three dividers for the millionth, billionth and trillionth part are based on words for "small" or, in the case of "nano-", for "dwarf" (as a direct counterpart to the "Giga-ntic" inverse).

The "micro-" prefix is the only one not indicated in Latin letters, using the Greek mu symbol instead. If that symbol is not available, the letter "u" is an acceptable substitute, but the "mc" often seen in pharmacy and nutritional information is not.

7. Not every prefix is derived from the Greek and Latin languages - in fact the one for 1 part in 10 to the 15th power is based on the Danish word for "fifteen". What is it?

Answer: femto-

The "femto-" prefix, just like its next smaller cousin, are the only ones based on a modern language and they also deviate from the pattern of counting groups of three zeroes. The prefix is rarely used outside time and length, but here's a more obscure one: If you were far out in the Milky Way, not within any stellar system, the pressure of the interstellar gas would be one femtopascal.

Please also note that all SI prefixes are case-sensitive as often the same letter is used for both an enlarging and a reducing prefix. All reducing prefixes and the magnifying ones up to 1000 ("kilo-") use lowercase initials and symbols, all larger ones uppercase. To add to the confusion, the m/M and p/P pairs both are not inverse to each other - the enlarging prefix in both cases has three zeroes more than the reducing one.

8. Where there is a fifth, there is a sixth following the same pattern: Derived from the Danish word for "eighteen", which prefix stands for the negative 18th power of 10?

Answer: atto-

The "atto-" prefix is the smallest one seen with any frequency in scientific literature. As an impression of scale, an attocoulomb is the positive charge of a single carbon nucleus (or the negative one of six electrons). Just like for the enlarging prefixes, the seventh and eighth level have been defined as well: They are "zepto-" and "yocto" - very similar to their inverses, but using lowercase letters and a hard consonant in the middle.

9. In 2010, an internet petition clamored for the addition of a new, larger, prefix to the SI system that would signify 10 to the 27th power. The mostly humorous term has still been used in a few publications - which is it?

Answer: Hella-

In 1960, the SI system was created with prefixes up to "Tera-" and "pico-", spanning 24 orders of magnitude. The first extension was done in 1964, adding the "femto-" and "atto-" prefixes. Interestingly enough, their inverse magnifying brethren were only added eleven years later, in 1975, balancing the system again at eight prefixes for each direction (the first six powers of one thousand plus the two for hundred and ten). The 1991 update expanded the scale by a factor of one million (two steps) in each direction.

The most popular of several expansion proposals of the early 21st century, the singular addition of "Hella-" (based on the Californian slang term) for the next larger level does not have any realistic chance of official recognition - not only is it more a humorous idea than a serious proposal, but it is also too limited in scope, not even suggesting an inverse prefix. Nonetheless, some sources have used it and Google does recognize it in conversions (try "hellameter to miles" as a search!)

10. A serious and easy to remember proposal for the extension of the SI prefix system beyond what would ever be needed was made in 2003 by Jim Blower. In his system, the ninth, tenth and eleventh thousand-step would be "Xona-", "Weka-" and "Vunda-". This should be enough for you to figure out which of his rather strange-sounding prefixes would stand for 10 to the 42nd power (1,000 to the 14th):

Answer: Sorta-

Mr. Blower's proposal is based on the observation that the seventh and eighth step use the letters Z and Y and extends from there. X thus becomes the ninth step, W the tenth and so on to A which then becomes the thirty-second (and several orders of magnitude larger than the number of particles in the known universe). Building further on the pattern "if it is large, it is uppercase and ends in the letter A, while the small one is lowercase and ends in o", the system can be read by anyone who knows the concept without memorizing any but the pre-1991 prefixes.

It does however not satisfactorily address the issue of duplicate abbreviation letters which first strike at 10 to the 39th power (T is already used for "Tera-" and thus cannot stand for "Treda-"); the combinations employed (TD, PP and MI) are rather arbitrary and do not easily work with existing units.

Source: Author WesleyCrusher

This quiz was reviewed by FunTrivia editor CellarDoor before going online.
Any errors found in FunTrivia content are routinely corrected through our feedback system.

You know kilo-, Mega-, Giga-, centi- and milli-, but do you have what it takes to prefix some very large or very small sizes? Let's take a look at the lesser used SI prefixes! (Numbers are in US system, thus one billion = 1000 million).

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