Education – Displays the percentage of users who received a correct / incorrect answer in a quiz

I'm building an educational app and wanted to try increasing engagement to show the percentage of people who chose each question option after the user answered.

Here is an example if my description was not clear.

Question options:

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After answering the question correctly:

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After answering the question incorrectly:

This is just a short model, but I wonder if that would encourage or discourage users. Would it increase engagement?

If I don't find an answer, I could try and test A / B and report back, but I was curious to see if anyone had already gone through this.

Even if you know of other case studies for educational quiz apps, that would be great !!

Stay safe, all of you :-]

Has anyone received Google Advertising Credits?

I recently heard that Google credits advertising to all AdWords accounts that have been active for at least a year. Unfortunately, my AdWords account has not been active for a few months, so I am not eligible for Google grants. Did someone credit you? If so, how much advertising credit has been added to each account? Curious to know! Thank you so much!

Wallet – Bitcoin sent, recipient claims not to have received

The address received 0.07014343 BTC in 3d727e3f4565e011c0348f813c2d5480210b6bae2003a0f7abaa949d1a7c599a. These coins have already been issued so that at least the recipient's wallet provider is informed of the transaction. Depending on the type of wallet, the recipient's account may not have been credited due to internal system problems.

Alternatively, the recipient has received the money and is trying to defraud you for an additional payment.

In both cases, your first transaction is successful and the recipient has to work with their wallet provider. You shouldn't send them any more money.

Verify that a transaction is complete

Based on the attention that this question receives, I will go through some of the best practices in verifying the finality / completion / status of a transaction.

In order for a Bitcoin transaction to be complete and irreversible, it must be summarized in one block.

To check whether a transaction has been closed, you can check a block explorer. Block Explorer are websites that read information from the blockchain and make it accessible to people who do not run their own nodes. Some commonly used Bitcoin discoverers are,, and (not affiliated with them).

If you look up the transaction, e.g. For example, using the link above, either a transaction details page or a form of an error not found is displayed.

If a transaction is not found, it is almost certain that it has not been cleared. In this case, you should aim for it Repetition the transaction instead of sending a new one. It is possible that the transaction has actually been sent and has not yet been picked up by Explorer. Submitting a second transaction can therefore result in a double payment.

If a transaction is found, it may be listed as unconfirmed. In this case, just wait until it is confirmed. If a transaction has already been confirmed, you should see an indication of the block into which it was mined (either in the form of a block number or a block hash that begins with a series of zeros). When a transaction is confirmed, it is complete and irreversible.

The recipient says that he did not receive the coins

There are a handful of scenarios in which the recipient may not see the coins even after the transaction is complete:

  1. The recipient's wallet is out of sync / is not updated correctly. This is a more common scenario if you're using Exchange or other hosted wallets, or using a normal wallet with a spotty or weak internet connection. In this case, the recipient must check with their wallet provider to find and credit the coins.
  2. The address is wrong – either you made a mistake when copying the address, or the recipient provided an incorrect address. In this case, you should work with the recipient to find out who needs to absorb the loss since the coins are most likely not recoverable.
  3. The recipient tries to cheat you. Once a transaction is complete, only the recipient can access the coins, find them, or otherwise try to work with them. If they insist that they have not received them, there is no problem on your part and you may be cheated.

Things to consider

  1. Do not use an Explorer recommended by the recipient. It's trivial to create an explorer that hides certain transactions and makes you think that when they're completed, they're not complete. Always use multiple third party explorers if you have to. Ideally, you should run your own instance of Bitcoin Core -txindex activated and check the transaction yourself, but for many users this is not possible in the short term.
  2. If you really need to resend the coins, first make a transaction in your own wallet that will send the entire balance to yourself and wait for this to be confirmed. This prevents you from accidentally paying twice if the original transaction simply wasn't sent properly.
  3. Be patient – it can take a few days for low fee transactions to be confirmed in times of high network activity. If you see an unconfirmed transaction, just wait.

Tweets cannot be received, but can be sent

In the past 3 days I haven't seen any replies to my tweets. I cannot interact with my followers. I can send tweets, but either my followers don't receive them or I don't receive them. I can't see their answers. Please help since Twitter doesn't have my account. My account is not locked or locked.

Payment – Sending Bitcoin to a wallet, but the user hasn't received one

At the time of writing, this transaction has 287 confirmations. That said, it was definitely irrevocably recorded. There can be no doubt about that. For large amounts, 6 confirmations are considered to be conclusive; for small amounts, many people accept 1 confirmation. 287 is beyond doubt.

The blockchain is the only truth. All data about the location of Bitcoin money is in the blockchain and nowhere else †.

There is no time when Bitcoin is on the move. It is always considered either by a node on the Bitcoin network as in your wallet or in the recipient's wallet and nowhere else.

The recipient Has received the money. If they say they don't have it either …

  • You sent the money to the wrong address, right
  • Your wallet doesn't tell them the truth
    (Maybe it's not synchronized with the blockchain) or
  • they are wrong or
  • they lie to you

† The use of Lightning networks and other off-chain systems should almost certainly not be considered as an actual Bitcoin movement until it has been recorded on the blockchain.