Remember to include 150 because any natural number is a factor of itself. The divisibility rules can be used to show that 1, 2, 3, 5, 6, and 10 are factors (and that 4 and 9 are not). Use factor pairs to find more factors: 15, 25, 30, 50, 75, and 150. Use division to check 7, 8, 11, 12, and 13. Since is less than 13, stop. The correct answer is 1, 2, 3, 5, 6, 10, 15, 25, 30, 50, 75, and 150.