Which of the following is a complete list of the positive factors of 60?
- 1, 2, 3, 4, 5, 6, 10, 15, 30, 60
- 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
- 2, 3, 4, 5, 6, 10, 12, 15, 20, 30
- 1, 2, 3, 5, 6, 10, 12, 15, 20, 60
Show answer and solution
Correct answer: B. 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
Pair the divisors: $1 \times 60$, $2 \times 30$, $3 \times 20$, $4 \times 15$, $5 \times 12$, $6 \times 10$. That gives 12 positive factors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60.
Option A misses 4, 12 and 20. Option C omits 1 and 60 (every positive integer has itself and 1 as factors). Option D drops 4.