Convert them at the airport or at shops nearby the airport.
About any bank will do this for you. Also Dollar coins are used as change at government machines such as train ticket machines and postage machines where you purchase stamps.
a dollar bill validator scans the bill and compares it to an image stored in memory
Vending machines can have multiple varieties of dollar bill validators of differing models and brands. While most vending machines do not come equipped to accept $2 bills (usually only $1's and occasionally $5's), there is the possibility that a vending machine was retrofitted with a special dollar bill validator to accept $2's.
No, all US bills regardless of denomination are the same size. This makes them easier to handle by machines.
1 dollar bills
Kate has 28 five-dollar-bills and 32 twenty-dollar-bills.
They make pens that detect fake bills, also the paper has small colored fibers.
Vending machines have laser scanners that can tell the difference between the bills.
You can exchange these at your local bank. However you can just as easily spend them. Use them in vending machines or transit fareboxes because they work better than paper bills. It also helps the economy because they cost less to produce than paper bills.
If you have ten, ten dollar bills you will have one hundred dollars. If you have 100 ten dollar bills, you will have 100 ten dollar bills...
100 hundred dollar bills is more money. 900 ten-dollar bills is a bigger stack of paper.