First figure out how many times the alligator population doubles in one year by dividing the number of months in a year by the number of months it takes the population to double: 12 months / 6 months = <<12/6=2>>2. The alligator population doubles twice.
Now double the alligator population once: 4 alligators * 2 = <<4*2=8>>8 alligators
Now double it again: 8 alligators * 2 = <<8*2=16>>16 alligators
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