Trying to understand multiple Bitcoin transactions in one block

[litehacker]

Look at this transaction:
http://blockchain.info/tx/87a99389373c8e2b7f99b890643c8901a3fc87fe1a8ba01e5b2cb5258816f353

Exactly how much money is coming from 1MPcX3ZmnkS6V9oqgv4bbt7bVPcHgYzvf3 and how much money is coming from 1LhEYFASYvauxCBvufzBwMyWgP4oThjNMQ?

Exactly how much money is going to 1CenyQGJDFdur6AzJ7BJv48F6Tmct6RQqU and how much money is going to 1LhEYFASYvauxCBvufzBwMyWgP4oThjNMQ?

How is it possible in this transaction that someone sends money to themselves?

[Kempelen]

Look at this transaction:
http://blockchain.info/tx/87a99389373c8e2b7f99b890643c8901a3fc87fe1a8ba01e5b2cb5258816f353

Exactly how much money is coming from 1MPcX3ZmnkS6V9oqgv4bbt7bVPcHgYzvf3 and how much money is coming from 1LhEYFASYvauxCBvufzBwMyWgP4oThjNMQ?

Exactly how much money is going to 1CenyQGJDFdur6AzJ7BJv48F6Tmct6RQqU and how much money is going to 1LhEYFASYvauxCBvufzBwMyWgP4oThjNMQ?

How is it possible in this transaction that someone sends money to themselves?

That transaction combines outputs from two different addresses, sends 0.105 BTC to 1CenyQGJDFdur6AzJ7BJv48F6Tmct6RQqU 0.105 BTC, and returns the change to the second input address.

[litehacker]

Why is money being sent back to the same wallet address?

I've seen this in multiple places.. Is this some kind of verification the client is doing?

[armenmerikyan]

I think it's the way bitcoin works, every transaction you make all the money is taken out and credited back to your account.

[kokjo]

the reason why there are multiple inputs and outputs in transactions are because the don't behave like 'normal-paper-and-coin'-money.
the way bitcoin operates is that you can spend a whole output or not, but not a fraction of it. so if i where to send you some bitcoin(5btc) but i have 2 outputs of 3btc i can spend both outputs(as inputs) and create 2 new outputs, one to you(5btc), and one back to myself(1btc).
like:

Tx:
input 1: reference to previous output - 3btc
input 2: reference to previous output - 3btc

output 1: new output - 5 btc
output 2: new output - 1 btc


its explained in satoshi's paper: http://bitcoin.org/bitcoin.pdf