Practice prime factorization.
1 is neither prime nor composite. It is called unity.
2 is prime.
3 is prime.
5 is prime.
7 is prime.
11 is prime.
13 is prime.
17 is prime.
19 is prime.
23 is prime.
29 is prime.
31 is prime.
37 is prime.
41 is prime.
43 is prime.
47 is prime.
53 is prime.
59 is prime.
61 is prime.
67 is prime.
71 is prime.
73 is prime.
79 is prime.
83 is prime.
89 is prime.
97 is prime.
101 is prime.