When audio messages are saved, they are saved to the iMessage conversation. You would have to scroll through the conversation to locate them.
You can save audio messages on your iPhone by changing your voice message settings in the Settings app so the messages never expire. If you don't change these settings, any voice message on your iPhone will expire two minutes after you first listen to them.
Therefore one million dollars in twenty dollar bills would weigh 50,000 grams or 50 kilos. There are 454 grams in a pound so there are 50,000 / 454 pounds of twenty dollar bills (about 110 pounds).
There are 50 pennies in a standard roll of USA pennies which equals 50 cents. What is this? Each penny weighs 2.500 grams, therefore 50 of them equal 125 grams.