There is a worldwide agreement between all countries to measure using the International System of Units (SI). Prefixes in this system represent multiples or subdivisions, and make it easier to understand and communicate when numbers get very big or very small.
The internationally agreed SI prefixes can be combined with every SI unit of measurement, for example:
Prefix Name |
Prefix Symbol |
Multiplier |
In practise |
milli |
m |
one thousandth |
millimetre (mm) = 0.001 metre = 10-3 metre |
milligram (mg) = 0.001 gram = 10-3 gram |
kilo |
k |
one thousand |
kilometre (km) = 1000 metre = 103 metre |
kilogram (kg) = 1000 metre = 103 metre |
For this challenge we asked participants to create two mnemonics, one for the SI prefix names for big numbers, and one for the SI prefix names for small numbers. You can see both in the chart below.
Multiplying Factor |
Name (symbol) |
Scientific Notation |
1 000 000 000 000 000 000 000 000 000 000 |
quetta (Q) |
1030 |
1 000 000 000 000 000 000 000 000 000 |
ronna (R) |
1027 |
1 000 000 000 000 000 000 000 000 |
yotta (Y) |
1024 |
1 000 000 000 000 000 000 000 |
zetta (Z) |
1021 |
1 000 000 000 000 000 000 |
exa (E) |
1018 |
1 000 000 000 000 000 |
peta (P) |
1015 |
1 000 000 000 000 |
tera (T) |
1012 |
1 000 000 000 |
giga (G) |
109 |
1 000 000 |
mega (M) |
106 |
1 000 |
kilo (k) |
103 |
100 |
hecto (h) |
102 |
10 |
deca (da) |
101 |
1 |
|
100 |
0.1 |
deci (d) |
10-1 |
0.01 |
centi (c) |
10-2 |
0.001 |
milli (m) |
10-3 |
0.000 001 |
micro (µ) |
10-6 |
0.000 000 001 |
nano (n) |
10-9 |
0.000 000 000 001 |
pico (p) |
10-12 |
0.000 000 000 000 001 |
femto (f) |
10-15 |
0.000 000 000 000 000 001 |
atto (a) |
10-18 |
0.000 000 000 000 000 000 001 |
zepto (z) |
10-21 |
0.000 000 000 000 000 000 000 001 |
yocto (y) |
10-24 |
0.000 000 000 000 000 000 000 000 001 |
ronto (r) |
10-27 |
0.000 000 000 000 000 000 000 000 000 001 |
quecto (q) |
10-30 |
Here’s an example of mnemonics we have come up with to get you started…
Daringly |
hungry |
kangaroos |
mock |
gorillas |
that |
playfully |
eat |
zucchini |
yet |
rarely |
quarrel |
deca |
hecto |
kilo |
mega |
giga |
tera |
peta |
exa |
zetta |
yotta |
ronna |
quetta |
Did |
centipedes |
munch |
my |
noodles? |
Please |
find |
all |
zingy |
yellow |
racoons |
quickly |
deci |
centi |
milli |
micro |
nano |
pico |
femto |
atto |
zepto |
yocto |
ronto |
quecto |
Find out more about the new SI prefixes