Looking at the above examples, we find there are some numbers which are not divisible by any other number other than one and itself without leaving a remainder. How many do we get? Arranging 6 marbles in equal groups Now we have 6 marbles and we have to arrange them in equal groups. In how many ways can you arrange them in equal groups? Arranging 7 marbles in equal groups There are only 2 ways Arranging 5 marbles in equal groups Assuming you have 5 marbles, in how many ways can you arrange them in equal groups? Let us start with examples to understand the concept of prime numbers. Numbers are very intriguing and there are so many ways to decipher them. Online Math Classes > Math Concepts > Number Systems > Prime Numbers