Facts to Commit to Memory
A reference sheet of useful facts: planetary distances, metric conversions, and data measurements.
Published January 1, 2022 ET
Earth and Solar System
| Measurement | Value |
|---|---|
| Diameter of Earth | 7,900 miles |
| Earth distance from Sun | 92 million miles |
| Earth orbital eccentricity | ~0.0167 |
| Diameter of Mars | 4,200 miles |
| Mars aphelion | 154 million miles |
| Mars perihelion | 128 million miles |
| Mars orbital eccentricity | ~0.0935 |
| Earth to Mars (closest) | 33 million miles |
| Earth to Mars (farthest) | 249 million miles |
| Neptune Orbital Diameter | 5.56 billion miles |
Galaxies
| Measurement | Value |
|---|---|
| Nearest Galaxy | Andromeda (~2.5 million light-years) |
| Size of Milky Way | ~105,700 light years |
| Size of Andromeda | ~220,000 light years |
Light-Year Calculation
- Seconds in a year: 365.2422 × 24 × 60 × 60 = 31,556,926 seconds (≈ 3.2E7)
- Speed of light: ≈ 3E8 m/s = ≈ 186,000 miles/s
- Distance of a light-year: 3E8 × 3.2E7 = 9.6E15 meters = 5.9 trillion miles
Imperial ↔ Metric Conversions
| Imperial | Metric |
|---|---|
| 1 Foot | 0.3048 meters |
| 1 Meter | 3.2808 feet |
| 1 Mile | 1,609 meters |
| 1 Mile | 5,280 feet |
Dividing by 7
Always follows the pattern 0.142857142857... (repeating 142857)
| Remainder | Result |
|---|---|
| 1/7 | 0.142857... |
| 2/7 | 0.285714... |
| 3/7 | 0.428571... |
| 4/7 | 0.571428... |
| 5/7 | 0.714285... |
| 6/7 | 0.857142... |
Large Numbers (Base 10)
Names correspond to distance (in sets of 3 zeros) from 1000. For E27: (27-3)/3 = 8 → Octillion
| Notation | Name |
|---|---|
| E3 | Thousand |
| E6 | Million |
| E9 | Billion |
| E12 | Trillion |
| E15 | Quadrillion |
| E18 | Quintillion |
| E21 | Sextillion |
| E24 | Septillion |
| E27 | Octillion |
| E30 | Nonillion |
| E33 | Decillion |
| E100 | Googol |
| E303 | Centillion |
| E^Googol | Googolplex |
Powers of 2
8 bits in a byte!
| Power | Value |
|---|---|
| 2^1 | 2 |
| 2^2 | 4 |
| 2^3 | 8 |
| 2^4 | 16 |
| 2^5 | 32 |
| 2^6 | 64 |
| 2^7 | 128 |
| 2^8 | 256 |
| 2^9 | 512 |
| 2^10 | 1,024 |
Data Measurements
Standard (Base 10)
| Unit | Bytes | Description |
|---|---|---|
| Kilobyte | 10^3 | Thousand bytes |
| Megabyte | 10^6 | Million bytes |
| Gigabyte | 10^9 | Billion bytes |
| Terabyte | 10^12 | Trillion bytes |
| Petabyte | 10^15 | Quadrillion bytes |
| Exabyte | 10^18 | Quintillion bytes |
RAM (Base 2)
| Unit | Bytes | Power of 2 |
|---|---|---|
| Kilobyte | 1,024 | 2^10 |
| Megabyte | 1,024^2 | 2^20 |
| Gigabyte | 1,024^3 | 2^30 |
| Terabyte | 1,024^4 | 2^40 |
| Petabyte | 1,024^5 | 2^50 |
| Exabyte | 1,024^6 | 2^60 |