PRIME NUMBERS

What does Prime Number mean?

The number which divides by itself are called the prime number but the condition is prime number must be a positive integer and it should be greater than 1.

Examples: 

17 is divisible by 1 and 17 only, So, it is a prime number.

15 is divisible by 1,3,5,15. So, it is not a prime number. 

Note: 1 itself is not a prime number.

So, the question should come into your mind i.e. 

How to find whether a given number is prime or not?

Let's make this more clear,

if the factors of the no. is more than two then it is not a prime no.

Ex- 6 has three factors 2*3*1 so it is not prime.

Let's take example of 2,329

Step1: If the no. ends with 0,2,4,6,8 then it is not prime.

Step2: Add the digit of the no. if the sum is divisible by 3 then it is not a prime no.

             2+3+2+9=16 

Step3: if the above steps are not true then find the Square root of the no.

           √2329 = 48.25

Step4: Divide all the prime less than 48.25 

           if we see the factors of 2329=17*137 Ohh! it is divisible by 17 & 17 is a prime number. So, 2329 is not a prime no.

Now it's your time to check,

Play with 149 & 137 and let us know whether it is prime or not?

Its all about prime numbers hope you like it !!! :)

 

 

 

 

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