There are 60 minutes in an hour.
Micah can type 20 x 60 = <<20*60=1200>>1200 words in an hour.
Isaiah can type 40 x 60 = <<2400=2400>>2400 words in an hour.
Isaiah can type 2400 - 1200 = <<2400-1200=1200>>1200 words more than Micah in an hour.
#### 1200