What's left of 21 million bitcoin

1.

The total number of bitcoins is 21 million

in 2009, when bitcoin was born, block reward was 50 bitcoins. Ten minutes after its birth, the first 50 bitcoins were generated, and the total amount of money at this time is 50. Then bitcoin grew at a rate of about 50 every 10 minutes. When the total amount reaches 10.5 million (50% of 21 million), the block reward will be halved to 25

when the total amount reaches 15.75 million (5.25 million new output, i.e. 50% of 1050), the block reward will be further halved to 12.5. The monetary system used to have no more than 10.5 million in four years, after which the total number will be permanently limited to about 21 million

extended data

monetary characteristics

1. Decentralization: bitcoin is the first distributed virtual currency, and the whole network is composed of users without a central bank. Decentralization is the guarantee of bitcoin's security and freedom

2. Global circulation: bitcoin can be managed on any computer connected to the Internet. No matter where you are, anyone can dig, buy, sell or collect bitcoin

3. Exclusive ownership: private key is needed to control bitcoin, which can be stored in any storage medium in isolation. No one can get it except the user himself

4. Low transaction cost: bitcoin can be remitted free of charge, but a transaction fee of about 1 bitfen will be charged for each transaction to ensure faster transaction execution

5, no hidden cost: as a means of payment from a to B, bitcoin has no cumbersome limit of quota and proceres. If you know the other party's bitcoin address, you can pay

6. Cross platform mining: users can explore the computing power of different hardware on many platforms

2. It is recommended not to participate in investment,

this kind of virtual currency is not a digital currency recognized by the central bank,

it is not protected by law,

the corresponding platform may collapse or run away at any time.

3. One of the controversial attributes of bitcoin is its fixed supply. At present, 25 new bitcoins are proced every 10 minutes, and the number is halved every four years. Overall, there won't be more than 21 million bitcoins & gt;. On the other hand, each bitcoin can be divided into 100 million shares (each is called 1 "cong"), if one cent is enough to buy a car, it will be troublesome to trade in US dollars, but even if bitcoin rises to the level of US dollars assumed above & gt; We will not encounter such problems. Therefore, in short, the total number of monetary units that will always exist is 2100 billion, that is 2100 trillion, or 250.899. In the square of choosing this value & gt; In fact, Nakamoto is much luckier or smarter than most people realize. First of all, this number is far less than 264-1, which is the largest integer that can be stored in the form of standard integer in a computer. If it exceeds that value, & gt; The value will return to zero like a odometer
secondly, however, there is a smaller threshold for the total number of "smart": the largest possible integer that can be represented in floating-point format. Integers are not the only numbers that computers can store; To deal with decimals, computers & gt; Use a format for floating point representation. Floating point notation is essentially a binary version of scientific notation. For example, here is a value you will encounter when you study physics:
mass of the earth: 5.972 1024 kg
mass of the sun: 1.989 1030 kg
speed of light: 2.998 108 M / s
light year: 9.460 1015 m
mass of proton: 1.672 10-27 kg
Planck length: 1.616 10-35 m
we can notice that, How does scientific notation allow you to represent all of these values with reasonable accuracy, even though they vary greatly in size. Floating point notation is essentially a binary scientific notation; When you store numbers & gt; When the word is 9.625, what your computer stores is "1.001101
* 1011" (in other words, it stores 0100000000100011
& gt; This is the same thing with high-precision sequence form). In this high-precision form, the coefficient (that is, the part that is not the exponent) has 52 bits. This means high precision (more refined & gt; Double precision floating point number is enough to store up to 253 numbers, but it can't be any higher. If it exceeds 253, you have to start cutting off the numbers at the end. Bitcoin's 250.9, the total number of "smart" in the form of index, is just & gt; OK, below this maximum
if we have integers, why should we care about floating-point values? Because more high-level programming languages (such as JavaScript) do not open low-level "floating point" and "integer representation", but only provide "number" representation for programmers; Concepts
– of course, in floating-point form. If Nakamoto chose 210 million instead of 21 million at that time, bitcoin programming in many languages would be much more troublesome than it is now
note that Stefan Thomas unfortunately didn't notice this in time when he wrote bitcoinjs, so that the library used a special "big number big
number" object instead of an ordinary number to store the tutorial output value; My own bifurcated bitcoin JS (along with other improvements) uses ordinary numbers.