## How to Check Whether A Number is Prime or Not

## Check Whether A Number is Prime or Not

This post talks about about how to check Whether a NUmber is Prime or not.Can the general rule to check for prime numbers be applied for all numbers .

To check whether a number is prime or not:

i)Take the square root of the number N.

ii)Round off the square root to the immediately lower integer. Call this number z.

iii)Check the divisibility of the number N by all prime numbers below z. If there is no prime number below the value of z which divides N, then the number N will be prime.

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## Question on Number of points with integer co-ordinates inside the triangle

## Number of points with integer co-ordinates inside the triangle

This Question is for finding Number of points with integer co-ordinates inside the triangle with the given condition.

(Q.)Consider a triangle drawn on the x-y plane with its three vertices at (41,0),(0,41) and (0,0), each vertex being represented by its (x , y) co-ordinates. The number of points with integer co-ordinates inside the triangle(excluding all the points on the boundary) is:

(i)780 (ii)800 (iii)820 (iv)741