Question

1. list the factors of 18.

Explanation:

Step1: Test divisibility by 1

$18 \div 1 = 18$, so 1 and 18 are factors.

Step2: Test divisibility by 2

$18 \div 2 = 9$, so 2 and 9 are factors.

Step3: Test divisibility by 3

$18 \div 3 = 6$, so 3 and 6 are factors.

Step4: Test divisibility by 4

$18 \div 4 = 4.5$, not integer, so 4 is not a factor.

Step5: Test divisibility by 5

$18 \div 5 = 3.6$, not integer, so 5 is not a factor.

Step6: Stop at $\sqrt{18} \approx 4.24$

No need to test numbers above this, as factors will repeat.

Answer:

1, 2, 3, 6, 9, 18