The total number of bitcoins is 21 million

1.

The concept of 21 million

bitcoin was first proposed by Nakamoto in 2009. According to Nakamoto's idea, open source software was designed and released, and P2P network was built on it. Bitcoin is a kind of P2P digital currency. Point to point transmission means a decentralized payment system

bitcoin is not issued in unlimited quantity, which is different from most currencies. Bitcoin does not rely on a specific currency issuer. But according to the specific algorithm, through a large number of calculations. Its circulation is controlled by software algorithms. The total number is 21 million

extended materials:

generation principle

starting from the essence of bitcoin, the essence of bitcoin is actually the special solution generated by a bunch of complex algorithms. A special solution is one of the infinite (in fact, bitcoin is finite) solutions that can be obtained from the equations. Every particular solution can solve the equation and is unique[ 10] In the metaphor of RMB, bitcoin is the serial number of RMB. If you know the serial number of a note, you have the note. The process of mining is to constantly seek the special solution of this equation system through a huge amount of calculation. This equation system is designed to have only 21 million special solutions, so the upper limit of bitcoin is 21 million

to mine bitcoin, you can download the special bitcoin computing tools, register various cooperation websites, fill the registered user name and password into the computing program, and then click the operation to officially start. After completing the installation of bitcoin client, you can directly obtain a bitcoin address. When others pay, you only need to paste the address to others, and you can pay through the same client. After installing the bitcoin client, it will distribute a private key and a public key. You need to back up your wallet data containing your private key to ensure that your property is not lost. Unfortunately, if the hard disk is completely formatted, personal bitcoin will be completely lost

2. 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.

3. The upper limit of bitcoin is not the exact figure of 21 million. 21 million is calculated according to the mining rules
in the first four years, 50 pieces were g out every ten minutes: 50 * 6 * 24 * (365 * 4 + 1) = 10519200 pieces
in the second four years, 25 pieces were g out every ten minutes: 25 * 6 * 24 * (365 * 4 + 1) = 5259600 pieces
according to the sum formula of infinite equal ratio sequence, the final total amount is infinitely close to 21038400 pieces (10519200 * 2)
as long as the mining rules are not changed, the number of bitcoins will never exceed 21038400

4. Cold wallet, also known as offline wallet, is a wallet that can be used without Internet connection. For example, the private key or mnemonic words are written on paper, professional hardware wallets, and some people make cold wallets with non networked devices. The advantage of using cold wallets is safety, but the disadvantage is that it is troublesome to trade and create wallets. Light wallet (SPV) SPV refers to "payment verification" rather than "transaction verification". Light wallet is a wallet implemented in thin client mode. It does not
store a complete blockchain, but only stores data related to itself. Therefore, it is small and can run on mobile phones, computers, Internet
pages, etc. The advantages of light wallet are: 1. It doesn't occupy memory; 2. It supports a variety of digital assets; 3. It has good user experience and is easy for beginners to use. The disadvantage is that transaction validation is slow.

5. There is an upper limit to the number of bitcoins, mainly because there is an upper limit to the solution set of the algorithms involved in the program. The algorithm is very complex. In theory, no computer has such powerful computing power that it can solve 51% of the solution set, that is, no one can control bitcoin

so far, the number of bitcoins has reached 12 million. To be exact, the maximum number of bitcoins should be 2099990000, but in fact, the current mining (mining) process is quite difficult - no less difficult than connecting 1000 home computers, and then continuously calculating for a month, it is not possible to dig out a bitcoin

I hope I can help you.

6. Due to the decentralized programming of the bitcoin system, only 25 bitcoins can be obtained every 10 minutes. By 2140, the maximum number of bitcoins in circulation will reach 21 million. In other words, bitcoin system is able to achieve self-sufficiency, resist inflation through coding, and prevent others from destroying these codes.

7. Yes, when it was released, it showed that its constant number was 21 million. With the passage of time and the efforts of the miners, the number left on the market is less than 2.5 million.