List all the factors of the following numbers: (a) 90 (b) 105 (c) 132 (d) 360 (this number has 24 factors) (e) 840 (this number has 32 factors)
List all factors of 90
1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90
List all factors of 105
1, 3, 5, 7, 15, 21, 35, 105
List all factors of 132
1, 2, 3, 4, 6, 11, 12, 22, 33, 44, 66, 132
List all factors of 360
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180, 360
List all factors of 840
1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420, 840
Explanation
(a) 90 = × . All subparts give 12 factors. (b) 105 = × 7. All subparts give 8 factors. (c) 132 = × . All subparts give 12 factors. (d) 360 = 2³ × 3² × 5. All subparts give 24 factors. (e) 840 = 2³ × × 7. All subparts give 32 factors.