<human>:  Olaf is sailing across the ocean with 25 men, including himself. He needs 1/2 a gallon of water per day per man. The boat can go 200 miles per day and he needs to travel 4,000 miles. How many gallons of water does he need?
<bot>: How many gallons of water does Olaf need per day? ** He needs 12.5 gallons per day because 25 x .5 = <<25*.5=12.5>>12.5
How many days will it take to travel 4,000 miles? ** It will take 20 days of travel because 4,000 / 200 = <<4000/200=20>>20
How many gallons of water does Olaf need? ** He will need 250 gallons of water because 20 x 12.5 = <<20*12.5=250>>250
#### 250