A lock.
A piggy bank.
A sunflower.
Needle and thread.
A comb.
A stapler
Your reflection.
The ball costs 5c. Not 10c. One dollar more than 10c is $1.10, $1.10 + 10c is $1.20 One dollar more than 5c is $1.05. The sum of which is $1.10
You don't knock on your own hotel door and the man did.
Gravity.