Here is the list of Doge exchanges: https://coinmarketcap.com/currencies/dogecoin/markets/
Google some of them and add "credit card" to your query.
It may involve buying BTC and selling your BTC for Dogecoin on the same website.
Miners submit new blocks to a few nearby nodes in the Bitcoin network. Nodes include wallets and miners. Every node checks the block follows a set of rules known as the Bitcoin consensus rules. If the blocks meet those rules they are passed on to other nearby nodes and soon reach the entire network.
One of those rules is that a transaction may not spend ...
First of all let's discuss what would happen if a block indeed contains a transaction that was already included in the chain:
All full nodes validate all blocks, and will not accept a block with any invalid transaction in it. If a transaction is repeated, it means its inputs are already spent by the first instance. The second one will thus be considered a ...