How many?
88 counts and estimates. The figure is the headline, but the method is the point — "how many grains of sand" is interesting because of how you estimate it, not because of the number.
Where the number is exact
A handful of these are not estimates at all but exact arithmetic. The number of ways to shuffle a deck is 52 factorial — about 8 × 10⁶⁷ — which is large enough that any properly shuffled deck has almost certainly never existed before in the history of the world. Chess positions, Rubik’s cube states and prime counts are the same kind of certainty.
Living things and the natural world
- How many people are there in the world? about 8.2 billion
- How many grains of sand are there on Earth? roughly 7.5 quintillion on the world's beaches
- How many ants are there in the world? about 20 quadrillion
- How many trees are there in the world? about 3 trillion
- How many insects are there? about 10 quintillion
- How many species are there? about 8.7 million
- How many people have ever lived? about 117 billion
- How many drops of water are there in the ocean? about 27 septillion
- How many fish are there in the sea? somewhere between 3 trillion and 100 trillion — nobody knows
- How many species are endangered? more than 45,000 assessed as threatened
- How many bees are there in the world? roughly 2 trillion managed honey bees
- How many birds are there in the world? about 50 billion wild birds
- How many bacteria are there on Earth? about 5 nonillion
- How many earthquakes are there each year? about 20,000 located a year — around 55 a day
- All 18
Space and the universe
- How many stars are there in the universe? about 200 billion trillion
- How many stars are there in the Milky Way? between 100 billion and 400 billion
- How many atoms are there in the universe? about 10^80
- How many galaxies are there? hundreds of billions — possibly 2 trillion
- How many satellites are in orbit? about 12,000 active satellites
- How many moons are there in the solar system? about 900 confirmed, and the number keeps moving
- How many planets are there in the galaxy? at least 100 billion — probably more planets than stars
- How many stars can you see with the naked eye? about 9,000 over the whole sky; roughly 2,500 at once
- How many constellations are there? exactly 88
- How much space junk is there? about 40,000 tracked objects, and over 130 million fragments too small to track
- How many asteroids are there? about 1.4 million catalogued
Things people built
- How many countries are there in the world? 195 — or 193, or 206, or 249, depending on who is counting
- How many cars are there in the world? about 1.5 billion motor vehicles
- How many planes are in the air right now? roughly 10,000 to 20,000 at any moment
- How many languages are there in the world? about 7,150 living languages
- How many McDonald's are there? about 43,000 in over 100 countries
- How many phones are there in the world? about 8.9 billion mobile connections — more than there are people
- How many nuclear weapons are there? about 12,200 warheads
- How many websites are there? about 1.1 billion hostnames — but only around 200 million active
- How many books have ever been published? about 130 million as of 2010 — probably over 200 million now
- How many airports are there in the world? about 45,000 with runways — but only around 4,000 with scheduled airline service
- How many ATMs are there in the world? about 3 million
- How many cities are there in the world? about 10,000 with over 50,000 people; 33 megacities over 10 million
- How many buildings are there in the world? somewhere between 1.5 and 4 billion
- How many computers are there in the world? roughly 2 billion personal computers in use
- All 29
Every day
- How many babies are born each day? about 360,000 — roughly four every second
- How many people die each day? about 170,000 — roughly two every second
- How many Google searches are made every day? roughly 8.5 billion — about 100,000 a second
- How many emails are sent every day? about 360 billion
- How many times does your heart beat in a lifetime? about 2.5 billion
- How many cups of coffee are drunk every day? roughly 2.5 billion
- How many photos are taken every day? roughly 5 billion a day — about 2 trillion a year
- How many steps do you take in a lifetime? roughly 150 million — about 110,000 km
- How many hours of video are uploaded to YouTube every minute? 500 hours a minute — about 720,000 hours a day
- How many pizzas are sold every day? somewhere between 3 and 8 million a day in the United States
- How many words do we speak a day? about 16,000
- How many breaths do you take in a lifetime? about 600 million
- How many messages are sent every day? about 100 billion on WhatsApp alone
The human body
- How many bones are in the human body? 206 in an adult — about 300 at birth
- How many cells are in the human body? about 30 trillion human cells, plus 38 trillion bacteria
- How many neurons are in the human brain? about 86 billion
- How many muscles are in the human body? about 600 skeletal muscles
- How many hairs are on your head? about 100,000
- How many taste buds do you have? about 2,000 to 8,000
- How long are all your blood vessels? commonly quoted as 100,000 km — but probably closer to 20,000
- How many base pairs are in human DNA? about 3.1 billion per copy — 6.2 billion in most cells
Numbers and possibilities
- How many combinations does a Rubik's Cube have? 43,252,003,274,489,856,000 — about 43 quintillion
- How many ways can you shuffle a deck of cards? about 8 × 10^67
- How many possible chess games are there? about 10^120 games; about 4.8 × 10^44 legal positions
- How many combinations are there in the lottery? 292,201,338 for Powerball
- How many digits of pi have been calculated? about 202 trillion
- How many possible passwords are there? 6.6 quadrillion for eight characters — 540 sextillion for twelve
- How many Sudoku puzzles are there? 6,670,903,752,021,072,936,960 completed grids
- How many prime numbers are there under a million? exactly 78,498
- How many possible positions are there in Go? about 2.08 × 10^170
Common questions
- How many ways can a deck of cards be shuffled?
- 52 factorial, about 8 × 10⁶⁷. That is large enough that a properly shuffled deck has almost certainly never occurred before in history.
- How reliable are these figures?
- It varies enormously and each page says which. Some are exact arithmetic; some are estimates with a factor-of-ten spread. Where a widely quoted figure has no traceable source, the page says so.