Thanks! 
I think the rabbit hole is actually bottomless! lolā¦ and each question always seems to raise 10 moreā¦
Watch out for the tags!.. be careful what you wish for 
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Donāt forget I have 2 jobs at the moment. 
Timeā; 
Your discussions will come into the mempool 
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Hi, I just had a look at the block explorer on Blockchain.com, and I was a bit surprised to see several BTC blocks that are over 1,300,000 bytes in size. I thought max blocksize was 1MB, and the biggest number I could find for the size of a megabyte is 1048576 bytes (https://en.wikipedia.org/wiki/Megabyte). So how can blocks be over 1048576 bytes in size?
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Hi! From what Iām reading it sounds like miners are free to pick and choose transactions from their mempool, and their main consideration seems to be transaction fees rather than the timestamp of the transactions. Should the timestamp not be the main consideration, even in the interest of the miner? If a miner would include a transaction in which Iām spending funds before the transaction in which I received those very funds, then it would appear Iām spending funds that I donāt have. This would invalidate the block, and he/she/they would have wasted time and money on a block that couldnāt possibly have won. Picking transactions in any other order than their chronological order seems self-defeating, regardless of the fees. Where am I wrong?
@Fabrice Hey Fabrice, Is it possible to have the inputs all be placed into a transaction and then sent to multiple wallets that you then control (minus the transaction fee of course) link back to your original owned private key? For example: I have input A of .1 btc and input B of .2btc. Would I be able to construct a transaction of both to equal .3 (minus transaction fee) sent back to my own wallet with a different public key?
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Yes, but you never should reuse the same address twice. HD wallets will create many addresses that your keys can control. (all derived from your bip39 mnemonic phrase 12 or 24 words + additional passphrase. )
You pick utxoās your private keys can use as input.
Change ownership to other bitcoin addresses.
A transaction is is just changing ownership of batches of bitcoin to some addresses.
For example, if you have 1 utxo of 10btc as input, you can pay Bob 2btc, Alice 5btc and 3btc to yourself. Just another address your private keys can control.
or better 2.9999btc (because you need to keep satoshis left for miners)
All in 1 transaction
Thatās because of Segwit. The block without signatures are still max 1mb.
Itās about block weight.
https://thenextweb.com/hardfork/2018/07/12/bitcoin-block-size/
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Yes neither the name neither the url are given.
Thank you!
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Hi,
anyone have the website used in this lesson?
Blockchain & Bitcoin 101 / Categories / Bitcoin Basics / Mining Visually demonstrated
Thanks
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Hey guys! Can anyone help me better understand the 4th question on the UTXO homework?
How could you use the notion of transaction inputs and outputs to increase privacy in your transaction?
I was under the impression that the transactions are already anonymous and made within a decentralised system. Is there a way to INCREASE the privacy in a transaction?
I read other answers that mentioned that privacy can be increased if you generate more outputs back to yourself.
Thanks!
You can use more addresses in the outputs.
For example you have 1utxo of 1btc and you need to pay 0.5 to someone.
Then You can use 1btc as input
0.5 as output on the address for the receiver and
0.5 (minus miner fee you can send to a different address of yours)
An outsider will see 1 input address and 2 different output addresses. He canāt know wich address is yours. In a HD Wallet, you will have many different addresses linked to your private keys wich only you know that all these addresses belong to you. Only if you combine more utxoās for inputs together in a transaction, people can assume the addresses in the input belong to the same person. But today there is also something like payjoin, which doesnāt guarantee it.
In Ethereum, we donāt use utxoās, but it uses an account model. So if you pay someone in ETH, you just subtract amount from account A and add it to account B. If you check an Ethereum address of someone you payed, you can see on the block explorer what his balance is and all tokens he has.
In Bitcoin, you have utxoās on many different addresses and only the owner of the private keys can know the total balance
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As there was of a example of 3 blocks in pow and incentives,only one block is allowed to get attached to the blockchain what about rest of the two blocks ,as ivan told they were all different ,doesnāt it will lead to loss of transaction data?
If 2 blocks get mined at the same time, the blockchain forks for a while with 2 versions of truth. Then it depends on the next miner on wich version he mines his block. The golden rule = longest chain (With most POW) Wins.
transactions that were in the stale block return to the mempool. Waiting to get picked up by another miner. (if they are not already included in the other competing block)
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Hi Guys
So to test UTXOās i sent a small amount from my wallet back to my wallet. When i checked the block i found my input and the transaction amount. When i checked the output there were two outputs equalling the total transaction amount. was the second output then created to hide my anonymity? If i was only sending to one address why two outputs?
So basically I have access to any bitcoin private key address that I can think of? But the reason itās still safe is because there are a gazillion possibilities? Does that also mean that taking a really stupid number or word or sentence gives you a functional, legitimate bitcoin address, just a very unsafe one? So then I would really be something you would let a computer doā¦ How safe are 24 words generated by a ledger nano s then?
I have a question around mining.
I understand miners select transactions from the mempool and are incentivised to select transactions with high sats/bite.
As a hypothetical, if a transaction entered the mempool with a ridiculous transaction fee, is it first in first served to select that transaction as a miner? or can thousands of miners grab that transaction and itās a rat race for the miners to get it into the block first?
In the lecture regarding the math behind mining Ivan said that the target gets lower if hash power increase and that the miners by changing the nonce try various hashes from 0 to infinite. But as far I understood SHA-256 gives binary numbers that are not going from 0 to infinite but from 0 to a certain number, a very very high number obviously, but not infinite.
The fact if that if the given hash given from SHA-256(nonce+tx+previous block hash) went from 0 to infinite it would be mathematically impossible to get a hash below a certain number since the probability to get a number below would tend to 0.
So I think that was slightly imprecise from a mathematical point of view. But what Iām interesting in is understanding if this is the case because if not I didnāt understand sth about the SHA-256 function or the mining process. Thank you very much in advance if someone could clarify 
It is my understanding that the senders of transactions that are willing to pay the highest fee to be included in the next block will be grabbed first and inserted into each pools block they are trying to solve. They want nothing more but to make as much money as possible.
If that particular transaction has the highest fee of all transactions in the mempool, it should be included in every mining poolās block that they are mining. Whoever solves the block first would more than likely have that high fee transaction included in it unless the winning miner had not received the transaction in itās mempool before choosing itās transactions (due to possibly being all the way across the world from the sender).
In a 100 years when all Bitcoins are mined there will be no incentive to mine and therefore no miners. At that point in time all transactions can be verified on the blockchain by nodes but no miners to append a block to the blockchain as a result of which all transactions would be verified but not confirmed. Is there a solution to this?