
- [List of national flags of sovereign states - Wikipedia](https://en.wikipedia.org/wiki/List_of_national_flags_of_sovereign_states)
- [Flags of the World Quiz - Sporcle](https://www.sporcle.com/games/g/worldflags)

## Flags that look alike

- Chad, Romania
- Senegal, Mali, Guinea
- Indonesia, Monaco, Poland
- New Zealand, Australia
- Ireland, Ivory Coast
- Norway, Iceland
- Venezuela, Ecuador, Colombia
- Luxembourg, Netherlands
- Slovenia, Russia, Slovakia
- Andorra, Moldova
- Croatia, Paraguay
- Bahrain, Qatar
- Kenya, South Sudan
- Italy, Mexico
- Haiti, Liechtenstein
- India, Niger
- Peru, Canada
- Bolivia, Ghana
- Hungary, Tajikistan
- Argentina, El Salvador, Nicaragua, Honduras
- Egypt, Iraq, Yemen, Sudan, Syria
- US, Malaysia, Liberia



Flags of the world

[Top]

Flags that look alike


## Countries and capitals

- [List of national capitals - Wikipedia](https://en.wikipedia.org/wiki/List_of_national_capitals)
- [Countries of the World Quiz - Sporcle](https://www.sporcle.com/games/g/world)
- [Capitals of the World Quiz - Sporcle](https://www.sporcle.com/games/g/worldcapitals)

| #  | Country                              | Capital                           |
|----|--------------------------------------|-----------------------------------|
|    | **Oceania**                          |                                   |
| 1  | Australia                            | Canberra                          |
| 2  | New Zealand                          | Wellington                        |
| 3  | Papua New Guinea                     | Port Moresby                      |
| 4  | Solomon Islands                      | Honiara                           |
| 5  | Nauru                                | Yaren*                            |
| 6  | Tuvalu                               | Funafuti                          |
| 7  | Vanuatu                              | Port Vila                         |
| 8  | [P] Palau                            | Ngerulmud                         |
| 9  | [M] Micronesia                       | Palikir                           |
| 10 | [M] Marshall Islands                 | Majuro                            |
| 11 | [K] Kiribati                         | South Tarawa                      |
| 12 | [Fi] Fiji                            | Suva                              |
| 13 | [S] Samoa                            | Apia                              |
| 14 | [T] Tonga                            | Nuku'alofa                        |
|    | **North America**                    |                                   |
| 1  | Canada                               | Ottawa                            |
| 2  | USA                                  | Washington, D.C.                  |
| 3  | Mexico                               | Mexico City                       |
| 4  | Guatemala                            | Guatemala City                    |
| 5  | Belize                               | Belmopan                          |
| 6  | El Salvador                          | San Salvador                      |
| 7  | Honduras                             | Tegucigalpa                       |
| 8  | Nicaragua                            | Managua                           |
| 9  | Costa Rica                           | San José                          |
| 10 | Panama                               | Panama City                       |
|    | **Caribbean**                        |                                   |
| 11 | Bahamas                              | Nassau                            |
| 12 | Cuba                                 | Havana                            |
| 13 | Jamaica                              | Kingston                          |
| 14 | [H] Haiti                            | Port-au-Prince                    |
| 15 | [D] Dominican Republic               | Santo Domingo                     |
| 16 | [K] Saint Kitts and Nevis            | Basseterre                        |
| 17 | [A] Antigua and Barbuda              | St. John's*                       |
| 18 | [D] Dominica                         | Roseau                            |
| 19 | [L] Saint Lucia                      | Castries                          |
| 20 | [V] Saint Vincent and the Grenadines | Kingstown                         |
| 21 | Grenada                              | St. George's                      |
| 22 | Trinidad and Tobago                  | Port of Spain                     |
| 23 | Barbados                             | Bridgetown                        |
|    | **South America**                    |                                   |
| 1  | Chile                                | Santiago                          |
| 2  | Argentina                            | Buenos Aires                      |
| 3  | Uruguay                              | Montevideo                        |
| 4  | Paraguay                             | Asunción                          |
| 5  | Bolivia                              | La Paz, Sucre                     |
| 6  | Peru                                 | Lima                              |
| 7  | Ecuador                              | Quito                             |
| 8  | Colombia                             | Bogota                            |
| 9  | Venezuela                            | Caracas                           |
| 10 | Guyana                               | Georgetown                        |
| 11 | Suriname                             | Paramaribo                        |
| 12 | Brazil                               | Brazilia                          |
|    | **Africa**                           |                                   |
| 1  | [M] Morocco                          | Rabat                             |
| 2  | [A] Algeria                          | Algiers                           |
| 3  | [T] Tunisia                          | Tunis                             |
| 4  | [L] Libya                            | Tripoli                           |
| 5  | [E] Egypt                            | Cairo                             |
| 6  | Mauritania                           | Mouakchott                        |
| 7  | Mali                                 | Bamako                            |
| 8  | Niger                                | Niamey                            |
| 9  | Chad                                 | N'Djamena                         |
| 10 | Sudan                                | Khartoum                          |
| 11 | South Sudan                          | Juba                              |
| 12 | Eritrea                              | Asmara                            |
| 13 | Djibouti                             | Djibouti                          |
| 14 | Ethiopia                             | Addis Ababa                       |
| 15 | Somalia                              | Mogadishu                         |
| 16 | Kenya                                | Nairobi                           |
| 17 | Uganda                               | Kampala                           |
| 18 | Rwanda                               | Kigali                            |
| 19 | Burundi                              | Bujumbura, Gitega                 |
| 20 | Tanzania                             | Dodoma                            |
| 21 | Mozambique                           | Maputo                            |
| 22 | South Africa                         | Cape Town, Pretoria, Bloemfontein |
| 23 | Lesotho                              | Maseru                            |
| 24 | Eswatini                             | Lobamba, Mbabane                  |
| 25 | Namibia                              | Windhoek                          |
| 26 | Botswana                             | Gaborone                          |
| 27 | Zimbabwe                             | Harare                            |
| 28 | Angola                               | Luanda                            |
| 29 | Zambia                               | Lusaka                            |
| 30 | Malawi                               | Lilongwe                          |
| 31 | Equitorial Guinea                    | Malabo                            |
| 32 | Gabon                                | Libreville                        |
| 33 | Rep. of Congo                        | Brazzaville                       |
| 34 | Dem. Rep. of Congo                   | Kinshasa                          |
| 35 | Senegal                              | Dakar                             |
| 36 | Gambia                               | Banjul                            |
| 37 | Guinea-Bissau                        | Bissau                            |
| 38 | Guinea                               | Conakry                           |
| 39 | Sierra Leone                         | Freetown                          |
| 40 | Liberia                              | Monrovia                          |
| 41 | Ivory Coast (Côte d'Ivoire)          | Abidjan, Yamoussoukro             |
| 42 | Burkina Faso                         | Ouagadougou                       |
| 43 | Ghana                                | Accra                             |
| 44 | Togo                                 | Lomé                              |
| 45 | Benin                                | Porto-Novo, Cotonou               |
| 46 | Nigeria                              | Abuja                             |
| 47 | Cameroon                             | Yaoundé                           |
| 48 | Central African Republic             | Bangui                            |
| 49 | Madagascar                           | Antananarivo                      |
| 50 | Comoros                              | Moroni                            |
| 51 | Mauritius                            | Port Louis                        |
| 52 | Cape Verde                           | Praia                             |
| 53 | São Tomé and Príncipe                | São Tomé                          |
| 54 | Seychelles                           | Victoria                          |
|    | **Europe**                           |                                   |
| 1  | Russia                               | Moscow                            |
| 2  | Norway                               | Oslo                              |
| 3  | Sweden                               | Stockholm                         |
| 4  | Finland                              | Helsinki                          |
| 5  | Iceland                              | Reykjavik                         |
| 6  | Ireland                              | Dublin                            |
| 7  | UK                                   | London                            |
| 8  | Portugal                             | Lisbon                            |
| 9  | Spain                                | Madrid                            |
| 10 | Andorra                              | Andorra la Vella                  |
| 11 | France                               | Paris                             |
| 12 | Monaco                               | Monaco                            |
| 13 | Belgium                              | Brussels                          |
| 14 | Luxembourg                           | Luxembourg                        |
| 15 | Netherlands                          | Amsterdam, The Hague              |
| 16 | Germany                              | Berlin                            |
| 17 | Denmark                              | Copenhagen                        |
| 18 | Poland                               | Warsaw                            |
| 19 | Czech Republic (Czechia)             | Prague                            |
| 20 | Switzerland                          | Bern*                             |
| 21 | Liechtenstein                        | Vaduz                             |
| 22 | Italy                                | Rome                              |
| 23 | Vatican City**                       | Vatican City                      |
| 24 | San Marino                           | San Marino                        |
| 25 | Malta                                | Valletta                          |
| 26 | Slovenia                             | Ljubljana                         |
| 27 | Croatia                              | Zagreb                            |
| 28 | Bosnia and Herzegovina               | Sarajevo                          |
| 29 | Montenegro                           | Podgorica                         |
| 30 | Albania                              | Tirana                            |
| 31 | North Macedonia                      | Skopje                            |
| 32 | Kosovo*                              | Pristina                          |
| 33 | Serbia                               | Belgrade                          |
| 34 | Austria                              | Vienna                            |
| 35 | Hungary                              | Budapest                          |
| 36 | Bulgaria                             | Sofia                             |
| 37 | Romania                              | Bucharest                         |
| 38 | Moldova                              | Chisinau                          |
| 39 | Ukraine                              | Kyiv/Kiev                         |
| 40 | Belarus                              | Minsk                             |
| 41 | Lithuania                            | Vilnius                           |
| 42 | Latvia                               | Riga                              |
| 43 | Estonia                              | Tallinn                           |
| 44 | Greece                               | Athens                            |
| 45 | Turkey                               | Ankara                            |
| 46 | Cyprus                               | Nicosia                           |
|    | **Asia**                             |                                   |
| 1  | Mongolia                             | Ulaanbaatar/Ulan Bator            |
| 2  | China                                | Beijing                           |
| 3  | Taiwan                               | Taipei                            |
| 4  | North Korea                          | Pyongyang                         |
| 5  | South Korea                          | Seoul                             |
| 6  | Japan                                | Tokyo                             |
| 7  | Nepal                                | Kathmandu                         |
| 8  | India                                | New Delhi                         |
| 9  | Maldives                             | Malé                              |
| 10 | Sri Lanka                            | Sri Jayawardenepura Kotte         |
| 11 | Bhutan                               | Thimphu                           |
| 12 | Bangladesh                           | Dhaka                             |
| 13 | Myanmar                              | Naypyidaw                         |
| 14 | Thailand                             | Bangkok                           |
| 15 | Laos                                 | Vientianne                        |
| 16 | Vietnam                              | Hanoi                             |
| 17 | Cambodia                             | Phnom Penh                        |
| 18 | Malaysia                             | Kuala Lumpur                      |
| 19 | Singapore                            | Singapore                         |
| 20 | Brunei                               | Banda Seri Begawan                |
| 21 | Indonesia                            | Jakarta                           |
| 22 | East Timor (Timor-Leste)             | Dili                              |
| 23 | Philippines                          | Manila                            |
| 24 | Pakistan                             | Islamabad                         |
| 25 | Afghanistan                          | Kabul                             |
| 26 | Iran                                 | Tehran                            |
| 27 | Iraq                                 | Baghdad                           |
| 28 | Saudi Arabia                         | Riyadh                            |
| 29 | Yemen                                | Sana'a                            |
| 30 | Oman                                 | Muscat                            |
| 31 | UAE                                  | Abu Dhabi                         |
| 32 | Qatar                                | Doha                              |
| 33 | Bahrain                              | Manama                            |
| 34 | Kuwait                               | Kuwait City                       |
| 35 | Syria                                | Damascus                          |
| 36 | Lebanon                              | Beirut                            |
| 37 | Israel                               | Jerusalem                         |
| 38 | Jordan                               | Amman                             |
| 39 | Georgia                              | Tbilisi                           |
| 40 | Armenia                              | Yerevan                           |
| 41 | Azerbaijan                           | Baku                              |
| 42 | Kazakhstan                           | Astana                            |
| 43 | [T] Turkmenistan                     | Ashgabat                          |
| 44 | [U] Uzbekistan                       | Tashkent                          |
| 45 | [K] Kyrgyzstan                       | Bishkek                           |
| 46 | [T] Tajikistan                       | Dushanbe                          |
| 47 | Palestine**                          | Ramallah                          |

## US states and capitals

- [List of states and territories of the United States - Wikipedia](https://en.wikipedia.org/wiki/List_of_states_and_territories_of_the_United_States#States)
- [US States Quiz - Sporcle](https://www.sporcle.com/games/g/states)
- [US Capitals Quiz - Sporcle](https://www.sporcle.com/games/g/uscapitals)

| State               | Capital        |
|---------------------|----------------|
| Alabama (AL)        | Montgomery     |
| Alaska (AK)         | Juneau         |
| Arizona (AZ)        | Phoenix        |
| Arkansas (AR)       | Little Rock    |
| California (CA)     | Sacramento     |
| Colorado (CO)       | Denver         |
| Connecticut (CT)    | Hartford       |
| Delaware (DE)       | Dover          |
| Florida (FL)        | Tallahassee    |
| Georgia (GA)        | Atlanta        |
| Hawaii (HI)         | Honolulu       |
| Idaho (ID)          | Boise          |
| Illinois (IL)       | Springfield    |
| Indiana (IN)        | Indianapolis   |
| Iowa (IA)           | Des Moines     |
| Kansas (KS)         | Topeka         |
| Kentucky (KY)       | Frankfort      |
| Louisiana (LA)      | Baton Rouge    |
| Maine (ME)          | Augusta        |
| Maryland (MD)       | Annapolis      |
| Massachusetts (MA)  | Boston         |
| Michigan (MI)       | Lansing        |
| Minnesota (MN)      | Saint Paul     |
| Mississippi (MS)    | Jackson        |
| Missouri (MO)       | Jefferson City |
| Montana (MT)        | Helena         |
| Nebraska (NE)       | Lincoln        |
| Nevada (NV)         | Carson City    |
| New Hampshire (NH)  | Concord        |
| New Jersey (NJ)     | Trenton        |
| New Mexico (NM)     | Santa Fe       |
| New York (NY)       | Albany         |
| North Carolina (NC) | Raleigh        |
| North Dakota (ND)   | Bismarck       |
| Ohio (OH)           | Columbus       |
| Oklahoma (OK)       | Oklahoma City  |
| Oregon (OR)         | Salem          |
| Pennsylvania (PA)   | Harrisburg     |
| Rhode Island (RI)   | Providence     |
| South Carolina (SC) | Columbia       |
| South Dakota (SD)   | Pierre         |
| Tennessee (TN)      | Nashville      |
| Texas (TX)          | Austin         |
| Utah (UT)           | Salt Lake City |
| Vermont (VT)        | Montpelier     |
| Virginia (VA)       | Richmond       |
| Washington (WA)     | Olympia        |
| West Virginia (WV)  | Charleston     |
| Wisconsin (WI)      | Madison        |
| Wyoming (WY)        | Cheyenne       |



Geography

This is a small list of things that feel useful/satisfying to carry around in your head. Sometimes they come in very handy.

## Measurements

- 1 inch = 2.54 cm
- 1 ft = 12 inch = 30.48 cm
- 1 mile = 1.609 km
- 1 oz = 28.34 g
- 1 gal = 4.54 L
- 1 US gal = 3.78 L
- 1 lb = 0.45 kg
- 1 kg = 2.2 lb
- 1 tbsp. = 15 ml
- 1 tsp. = 5 ml
- 1 hectare = 10000 sq. m (100m x 100m) = 2.47 acres
- 1 acre = 4046.85 sq. m (66ft x 660ft) ~ 40% of hectare

## Greek alphabet

| Uppercase | Lowercase | Name |
|-----------|-----------|---------|
| Α | α | alpha |
| Β | β | beta |
| Γ | γ | gamma |
| Δ | δ | delta |
| Ε | ε | epsilon |
| Ζ | ζ | zeta |
| Η | η | eta |
| Θ | θ | theta |
| Ι | ι | iota |
| Κ | κ | kappa |
| Λ | λ | lambda |
| Μ | μ | mu |
| Ν | ν | nu |
| Ξ | ξ | xi |
| Ο | ο | omicron |
| Π | π | pi |
| Ρ | ρ | rho |
| Σ | σ / ς | sigma |
| Τ | τ | tau |
| Υ | υ | upsilon |
| Φ | φ | phi |
| Χ | χ | chi |
| Ψ | ψ | psi |
| Ω | ω | omega |

## Powers of 2

| n | 2^n | Mnemonic |
|----|------|----------|
| 0 | 1 | |
| 1 | 2 | |
| 2 | 4 | |
| 3 | 8 | |
| 4 | 16 | |
| 5 | 32 | |
| 6 | 64 | 64 starts with 6 |
| 7 | 128 | |
| 8 | 256 | |
| 9 | 512 | |
| 10 | 1024 | 1024 starts with 10 |
| 20 | 1048576 | ~1 million |
| 30 | 1073741824 | ~1 billion |
| 40 | 1099511627776 | ~1 trillion |

## Integer ranges

- Signed: $-2^{n-1}$ to $2^{n-1}-1$ 
- Unsigned: $0$ to $2^n-1$

| Bits | Min | Max |
|------|----------------------------|----------------------------|
| i8 | -128 | 127 |
| i16 | -32,768 | 32,767 |
| i32 | -2,147,483,648 | 2,147,483,647 |
| i64 | -9,223,372,036,854,775,808 | 9,223,372,036,854,775,807 |
| u8 | 0 | 255 |
| u16 | 0 | 65,535 |
| u32 | 0 | 4,294,967,295 |
| u64 | 0 | 18,446,744,073,709,551,615 |

## Squares and cubes

| | Square | Cube |
|-------|--------|-------|
| 1 | 1 | 1 |
| 2 | 4 | 8 |
| 3 | 9 | 27 |
| 4 | 16 | 64 |
| 5 | 25 | 125 |
| 6 | 36 | 216 |
| 7 | 49 | 343 |
| 8 | 64 | 512 |
| 9 | 81 | 729 |
| 10 | 100 | 1000 |
| 11 | 121 | 1331 |
| 12 | 144 | 1728 |
| 13 | 169 | 2197 |
| 14 | 196 | 2744 |
| 15 | 225 | 3375 |
| 16 | 256 | 4096 |
| 17 | 289 | 4913 |
| 18 | 324 | 5832 |
| 19 | 361 | 6859 |
| 20 | 400 | 8000 |

## NATO phonetic alphabet

[[Wikipedia](https://en.wikipedia.org/wiki/NATO_phonetic_alphabet)]

Alfa, Bravo, Charlie, Delta, Echo, 
Foxtrot, Golf, Hotel, India, Juliett, 
Kilo, Lima, Mike, November, Oscar, 
Papa, Quebec, Romeo, Sierra, Tango, 
Uniform, Victor, Whiskey, Xray, Yankee, 
Zulu

## SI prefixes

[[Wikipedia](https://en.wikipedia.org/wiki/International_System_of_Units#Prefixes)]

quetta, ronna, yotta, zetta, exa, 
peta, tera, giga, mega, kilo, 
unit (10^0), 
milli, micro, nano, pico, femto, 
atto, zepto, yocto, ronto, quecto

## Paper sizes

[[International standard paper sizes](https://en.wikipedia.org/wiki/International_standard_paper_sizes)]

(Aspect ratio of sqrt(2))

- A0: 841 × 1189 (1 sq. m area)
- A1: 594 × 841
- A2: 420 × 594
- A3: 297 × 420
- A4: 210 × 297 (1/16 of A0)

## Poker

[[List of poker hands](https://en.wikipedia.org/wiki/List_of_poker_hands)]

| Rank | Name | Description |
|------|-----------------|-----------------------------------------------|
| 1 | Royal Flush | A, K, Q, J, 10 of the same suit |
| 2 | Straight Flush | 5 cards of the same suit, in sequence |
| 3 | Four of a Kind | 4 cards of the same rank |
| 4 | Full House | 3 of a kind + a pair |
| 5 | Flush | 5 cards of the same suit, not in sequence |
| 6 | Straight | 5 consecutive cards of different suits |
| 7 | Three of a Kind | 3 cards of the same rank |
| 8 | Two Pair | 2 cards of one rank + 2 cards of another rank |
| 9 | One Pair | 2 cards of the same rank |
| 10 | High Card | The highest card in the hand |

## Misc

- [List of TCP and UDP port numbers](https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers)
- [List of HTTP status codes](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes)
- [List of HTTP header fields](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields)
- Alphabet backward: `ZYX W VUTS RQ PON MLK JIHG FED CBA`