# How Many is “Many,” or What is the Largest Possible Number?

As soon as a child gets to know the difference between “singular” and “plural,” he/she unconsciously wants to find out how many is “many,” or whether there is a number to quantify everything in the Universe.

As adults, we understand that there is no such number – we can always add “one” to any monstrously large number to make it even larger. We can create a number with an endless row of zeros to satisfy our curiosity but, frankly speaking, it’s a waste of time. Numbers should mean something and possess practical utility; in other words, they should be invented to quantify something.

## It’s important to know

When it comes to monstrously large numbers, scientists traditionally use approximation. For example, it is believed that there are 1021 (1 followed by 21 zeros) stars in the observable universe. It’s only natural that these calculations are approximate. In fact, the exact number of stars can be 1,564,861,615,140,168,357,973 or even 9,999,999,999,999,999,999,999 – for scientists, it’s more important to determine of how many digits this number consists rather than to specify the very digits. By the way, 1021 is called a sextillion.

## Large, and larger

You can hardly find a person who doesn’t know that 103 is a thousand, 106 is a million, or 109 is a billion - let’s explore larger numbers:

• 1011, one hundred billion, is the number of people who have ever lived on Earth;
• 1012, or a trillion, - a trillion seconds ago, mammoths were still alive;
• 1015, or a quadrillion, is the approximate number of ants on Earth;
• 1024, or a septillion, - 1024 kg is the mass of Earth;
• 1026m is the diameter of the observable universe;
• 1051, or a sexdecillion, is the number of atoms our planet composed of;

• There are 1080 elementary particles in the observed universe;
• 10100, or a googol, is just a round number;
• There are 10185 Planck volumes – a Planck volume is a unit of length that can be approximated to 10-35m – in the observable universe. Since the Planck volume is the smallest unit of length, 10185 is the largest number used for quantitation.
• There are numbers larger than 10185 – Graham’s number is so unimaginably large that its digital representation won’t fit in the observable universe, even if each digit will occupy one Planck volume.
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