A Walk Through The World Of Prime Numbers

Mathematics is a fascinating subject, full of interesting topics which children can explore, understand and fall in love with. As a parent, you need to ensure that your children get a strong foundation of Math from an early age so that doing well in the subject becomes a cakewalk for them.

In this article, we will discuss Prime Numbers, which is one of the fundamental concepts of Math and has application everywhere. Read on to know all about Prime numbers and tell your children about them.

What is a Prime Number?

A prime number is a number which is either divisible by 1, or by itself. For example, numbers like 2, 3, 5, 7, 11, 13, 17, 19, 23, 29 are called Prime Numbers as they cannot be divided by any other number than itself.

Except for number 2, which is an even number, all prime numbers are odd numbers as they are not divisible by 2.

How to find out if a number is prime or composite?

Here are two rules that will make it easy for you to identify prime numbers:

Rule 1: If a number can be divided into equal parts, it is a composite number and not a prime number.

Since prime numbers cannot be divided by 2, they cannot be divided into equal parts.

Hence, the numbers like 4, 6, 8, 10, 12 are numbers which can be divided into equal groups are not prime, but composite numbers.

For example, 12 can be divided into:

Two groups of 6 (6+6)

Three groups of 4 (4+4+4)

Four groups of 3 (3+3+3+3), or

Six groups of 2 (2+2+2+2+2+2)

Hence, 12 is a composite number.

Rule 2: A prime number is a number that can be divided only by itself and 1

If you take the number 7, you can divide it by only 1 and 7. So, it is a prime number. Similarly, numbers such as 13, 23, 29, 43, 47 and so on are also prime numbers for the same reason.

So let us now see whether the numbers 5, 8, and 17 are prime or composite.

5 can only be divided by itself and 1. Since this fulfils Rule 2 mentioned above, we can safely say that 5 is a prime number.

8 can be divided by 1, 2, 4 and 8 itself. This fulfils Rule 1. Hence it is a composite number.

17 can only be divided by only 1 and itself. So, it is a prime number.

Teach your child these two rules and ask her to apply this method to quickly identify prime and composite numbers. Once the logic becomes clear, your child will develop an eye for identifying them.

Following a prime numbers list will be helpful here. There are a total of 25 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

Prime Factorization:

The first thing that needs to be done to identify a prime number is to see if the number is divisible by any other number smaller than itself, except 1. If yes, then make a list of those numbers. These numbers are called ‘Prime Factors’ and the process of finding out these factors is called ‘Prime Factorization’.

Prime Factorization includes finding out the prime numbers with which a number can be divided. We have to keep dividing until we get the original number as the result and the numbers that remain are only prime. While dividing the number with prime numbers, a point needs to be reached where it cannot be divided anymore.

For a better idea, let’s try to find out the prime factors of 200:

200  = 2*100

= 2*2*50

= 2*2*2*25

=2*2*2*5*5

So the prime factors of 200 are 2,2,2,5,5, which can also be written as 2³ x 5²

Similarly, if we take another example of 189, we will get the following results:

189 = 3*63

= 3*3*21

= 3*3*3*7

So,  the prime factors of 189 are 3,3,3,7, or 3³x7

Is 1 a prime number?

The smallest prime number, according to Mathematicians, is number 2. It is the smallest among all the prime numbers and it follows Rule 2 (as mentioned earlier) of having two divisors, 1 and itself.

1 is not a prime number as it doesn’t have two factors and can only be divided by itself. It can be the smallest number, but it does not have two divisors. So, 1 is not considered to be a prime number by Mathematicians.

I hope by now you have understood the process clearly. Take a few numbers, make your child find its prime factors independently and we are sure she will never face any difficulty in identifying prime numbers again.

Why should your child learn about prime numbers?

The understanding of prime numbers will be very important for your children throughout their lifetime, especially in the higher classes. Explain the concepts clearly, and make them do lots of exercises to improve their mental Math and application skills.Go through this Math Topics

At Cuemath, they have developed an amazing Math learning program which teaches children Prime Numbers in a fun-filled and interactive way. There are thousands of Cuemath centres across India, run by experienced teachers who are specially trained to make children of all ages and aptitude levels fall in love with Math. We believe that a clear understanding of prime numbers is critical for any child to become successful in life, and the program includes special games and activities to give them a clear understanding of it.

Browse the list of Cuemath centres in your area and talk to us if you have any questions about how the Cuemath program can help your child to become a master of Math.

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