Metric prefixes, from tera to pico
The 12 most used of the 24 SI prefixes. NIST also lists larger ones (peta to quetta) and smaller ones (femto to quecto). Capital and small letters matter: M is mega, m is milli. NIST spells the prefix for ten "deka"; some countries write "deca."
Every metric unit uses the same set of prefixes, so learning these twelve unlocks meters, grams, liters, watts and bytes all at once. Each step is a power of ten, which is what makes the metric system easy to convert.
Build from first principles: each prefix means 'times ten to some power.' From kilo down to milli the steps go one power of ten at a time (kilo, hecto, deka, base, deci, centi, milli: "Kind Hippos Dance Barefoot During Chilly Mornings"), and outside that range they jump three powers at a time (mega, giga, tera; micro, nano, pico). Chunk them that way: the big jumps, the small steps, the tiny jumps.
Encode make it vivid → Space bring it back on day 1, 3, 7, 21 → Retrieve pull it from your head. From the infographic Remember It on Purpose.
Metric prefixes, from tera to pico
| Prefix | Symbol | Power of ten | As a number |
|---|---|---|---|
| tera | T | 10^12 | 1,000,000,000,000 |
| giga | G | 10^9 | 1,000,000,000 |
| mega | M | 10^6 | 1,000,000 |
| kilo | k | 10^3 | 1,000 |
| hecto | h | 10^2 | 100 |
| deka | da | 10^1 | 10 |
| deci | d | 10^-1 | 0.1 |
| centi | c | 10^-2 | 0.01 |
| milli | m | 10^-3 | 0.001 |
| micro | μ | 10^-6 | 0.000001 |
| nano | n | 10^-9 | 0.000000001 |
| pico | p | 10^-12 | 0.000000000001 |
Build from first principles: each prefix means 'times ten to some power.' From kilo down to milli the steps go one power of ten at a time (kilo, hecto, deka, base, deci, centi, milli: "Kind Hippos Dance Barefoot During Chilly Mornings"), and outside that range they jump three powers at a time (mega, giga, tera; micro, nano, pico). Chunk them that way: the big jumps, the small steps, the tiny jumps. · teddyrookbook.com/memory/challenges/metric-prefixes/
Sources
- NIST: Metric (SI) Prefixes
- NIST Handbook 44 (2024), Appendix C: General Tables of Units of Measurement
Checked October 30, 2026. Progress is kept on this device only (per learner). More lists: all memory challenges · memory games.