When you send a message on Facebook Messenger you'll see a circle with a tick inside appear next to the text box. Then, if the recipient opens it, this will disappear and be replaced by the person's icon. Then, open the app and read the new message without the sender knowing.
When you receive a message from a Messenger chat, you can read that message without the person knowing- just switch on your airplane mode. This removes Messenger's ability to process the fact that you have viewed the message because there is no internet connection.
Go to Settings and tap on Messages. An option called Send Read Receipts can be found here. Toggle it off to disable the ability completely.
100,000,000 penniesThere are 100,000,000 pennies in one million dollars.
So in one million dollars the are four million quarters.