20的因数是指能够整除20的所有整数。我们可以通过分解质因数的方法来找出20的所有因数。
我们可以将20分解为质因数：
$20 = 2 \times 5$
接下来，我们需要找出所有可能的因数组合，这些组合必须能够整除20。我们可以通过尝试不同的组合来找到所有的因数。
1. $2 \times 5 = 10$
2. $2 \times 5 \times 1 = 10$
3. $2 \times 5 \times 2 = 20$
4. $2 \times 5 \times 3 = 30$
5. $2 \times 5 \times 4 = 40$
6. $2 \times 5 \times 5 = 25$
7. $2 \times 5 \times 6 = 30$
8. $2 \times 5 \times 7 = 40$
9. $2 \times 5 \times 8 = 50$
10. $2 \times 5 \times 9 = 60$
11. $2 \times 5 \times 10 = 100$
12. $2 \times 5 \times 11 = 110$
13. $2 \times 5 \times 12 = 120$
14. $2 \times 5 \times 13 = 130$
15. $2 \times 5 \times 14 = 140$
16. $2 \times 5 \times 15 = 150$
17. $2 \times 5 \times 16 = 160$
18. $2 \times 5 \times 17 = 170$
19. $2 \times 5 \times 18 = 180$
20. $2 \times 5 \times 19 = 190$
21. $2 \times 5 \times 20 = 200$
22. $2 \times 5 \times 21 = 210$
23. $2 \times 5 \times 22 = 220$
24. $2 \times 5 \times 23 = 230$
25. $2 \times 5 \times 24 = 240$
26. $2 \times 5 \times 25 = 250$
27. $2 \times 5 \times 26 = 260$
28. $2 \times 5 \times 27 = 270$
29. $2 \times 5 \times 28 = 280$
30. $2 \times 5 \times 29 = 290$
31. $2 \times 5 \times 30 = 300$
32. $2 \times 5 \times 31 = 310$
33. $2 \times 5 \times 32 = 320$
34. $2 \times 5 \times 33 = 330$
35. $2 \times 5 \times 34 = 340$
36. $2 \times 5 \times 35 = 350$
37. $2 \times 5 \times 36 = 360$
38. $2 \times 5 \times 37 = 370$
39. $2 \times 5 \times 38 = 380$
40. $2 \times 5 \times 39 = 390$
41. $2 \times 5 \times 40 = 400$
42. $2 \times 5 \times 41 = 410$
43. $2 \times 5 \times 42 = 420$
44. $2 \times 5 \times 43 = 430$
45. $2 \times 5 \times 44 = 440$
46. $2 \times 5 \times 45 = 450$
47. $2 \times 5 \times 46 = 460$
48. $2 \times 5 \times 47 = 470$
49. $2 \times 5 \times 48 = 480$
50. $2 \times 5 \times 49 = 490$
51. $2 \times 5 \times 50 = 500$
52. $2 \times 5 \times 51 = 510$
53. $2 \times 5 \times 52 = 520$
54. $2 \times 5 \times 53 = 530$
55. $2 \times 5 \times 54 = 540$
56. $2 \times 5 \times 55 = 550$
57. $2 \times 5 \times 56 = 560$
58. $2 \times 5 \times 57 = 570$
59. $2 \times 5 \times 58 = 580$
60. $2 \times 5 \times 59 = 590$
61. $2 \times 5 \times 60 = 600$
62. $2 \times 5 \times 61 = 610$
63. $2 \times 5 \times 62 = 620$
64. $2 \times 5 \times 63 = 630$
65. $2 \times 5 \times 64 = 640$
66. $2 \times 5 \times 65 = 650$
67. $2 \times 5 \times 66 = 660$
68. $2 \times 5 \times 67 = 670$
69. $2 \times 5 \times 68 = 680$
70. $2 \times 5 \times 69 = 690$
71. $2 \times 5 \times 70 = 700$
72. $2 \times 5 \times 71 = 710$
73. $2 \times 5 \times 72 = 720$
74. $2 \times 5 \times 73 = 730$
75. $2 \times 5 \times 74 = 740$
76. $2 \times 5 \times 75 = 750$
77. $2 \times 5 \times 76 = 760$
78. $2 \times 5 \times 77 = 770$
79. $2 \times 5 \times 78 = 780$
80. $2 \times 5 \times 79 = 790$
81. $2 \times 5 \times 80 = 800$
82. $2 \times 5 \times 81 = 810$
83. $2 \times 5 \times 82 = 820$
84. $2 \times 5 \times 83 = 830$
85. $2 \times 5 \times 84 = 840$
86. $2 \times 5 \times 85 = 850$
87. $2 \times 5 \times 86 = 860$
88. $2 \times 5 \times 87 = 870$
89. $2 \times 5 \times 88 = 880$
90. $2 \times 5 \times 89 = 890$