I think ATM machies works on the most shittiest algorithms ever. One day me and my friend went to an ATM to withdraw ₹500 for me and ₹300 for him.
I entered 500 and got five ₹100 notes. But my friend, he had to withdraw ₹500 because, guess what, the ATM didn't have any ₹100 remaining.
the message "Available denominations are: 500 and 2000" was shown.
If only it had given me a ₹500 note, then he could get his ₹300 too.