John bought 64 pens at a bookshop. Each pen cost $2.30. How much change did he receive if he paid $188?
The total cost of the pens is 64*$2.30 = $<<64*2.3=147.20>>147.20
The change he received is $188-$147.20 = $<<188-147.20=40.80>>40.80. Answer: \boxed{40}.