Carlton runs 3 miles each day from Monday through Friday. He runs 5 miles on Saturday and 5 miles on Sunday. He calculates that he will run 900 miles total in 41 weeks.

Carlton is incorrect because if you multiply 3 miles by the 5 weekdays, you get 15miles. If you add that to the 10miles Carlton runs over Saturday and Sunday, you end up with 25miles. Then, you multiply 25miles by 41weeks and get 1,025miles over the course of the 41 weeks.