Grayson has 100 questions on a test. He answers some of the questions for 2 hours, taking two minutes for each answer, then realizes he doesn't know the rest of the questions. How many questions does Grayson leave unanswered when he submits his test?
How many minutes did Grayson take? ** Each hour contains 60 minutes, so after 2 hours he took 2*60 = <<2*60=120>>120 minutes.
How many questions did Grayson answer? ** If each question takes two minutes, then he answered 120/2 = <<120/2=60>>60 questions.
How many questions does Grayson leave unanswered? ** Unanswered questions is 100-60 = <<100-60=40>>40 questions
#### 40