The composite numbers between 10 and 20 are: 12, 14, 15, 16 and 18 which have more than 2 factors.
To find a composite number, we find the factors of the given number. The best way to determine a composite number is to do a divisibility test. The divisibility test helps us determine if the number is prime or composite. Divisibility means that one number is divided completely (without remainder) by another number.