Prime numbers from 1 to 100, and composite numbers

All numbers, like 2, 4, 7, 17, etc, always have two factors. One is the number itself, and the other s the number 1, since 1 is the factor of all numbers. For example, the number 10 has factors 10 and 1.

In addition to this, some numbers also have many other factors like  10 has two more factors 5 and 2. These numbers that have more than the two predetermined factors, are called composite numbers.

The numbers that do not have the other factors except 1 and the number itself, are called prime numbers. The following is a list of all prime numbers from 1 to 100:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.

The composite numbers from 1 to 100 are naturally all the numbers other than the above ones, except 1, because 1 is a unique number.

Why is 1 neither prime, nor composite?

Because 1 has only one factor, itself. Thus it neither falls into the category of prime numbers nor in the category of composite numbers.