Is there a transaction confirmation for ethereum like there is for bitcoin? I sent 73 etherium to an exchange and they show only 64. How can I verify that they received all 73?
Yes https://etherscan.io/ is the blockchain explorer for Ethereum Blockchain.
It is basically a search engine that allows users to easily lookup, confirm and validate transactions that have taken place on the Ethereum Blockchain
Get the transaction hash from your wallet or node, and search for it on etherscan.io.
You can see the inputs and outputs of the transaction, and verify that the funds were transferred to their account.
This should be enough to get you the proof you need.