I recently sent .9 BTC from my Coinbase account to a Blockchain.info wallet, but the numbers I see are confusing. According to my Blockchain app, the transaction was for .90130821 BTC, with a fee of .0001 BTC (for the miners, I get that). The .9 BTC made it to my wallet, but the remaining .00120821 went somewhere else. Because of this, I have three questions...
1) Why is the transaction amount more than the specific .9 BTC I wanted to send?
2) How was that amount (.00130821 BTC) chosen?
3) Where did the .00120821 BTC get sent?