18 and 20
Prime numbers have two factors, composite numbers have more than two.
Prime numbers have two factors. Composite have more than two. Neither (one and zero) have less than two.
Prime numbers have two factors; composite numbers have more than two.
Composite numbers are integers that have more than two factors.
9 and 15 are the only two odd composite numbers less than twenty.
Prime numbers have two factors. Composite numbers have more than two. Numbers with less than two are neither.
Composite numbers have more than two factors. So, the numbers which have two or less than two factors are not composite numbers. Numbers which have exactly two factors are prime numbers. 1 is an exceptional case because it is neither prime nor composite since it has only one factor which is 1.
18 and 20
Prime numbers have two factors, composite numbers have more than two.
Prime numbers have two factors. Composite numbers have more than two.
99 is one of them and all other numbers less than 100 that have more than two factors in them.
Prime numbers have two factors, composite numbers have more than two.
Composite numbers have more than two factors.
Composite numbers are numbers that have more than two factors.
Prime numbers have two factors. Composite have more than two. Neither (one and zero) have less than two.
Prime numbers have two factors; composite numbers have more than two.