Number Systems-1


Well i will begin with concepts of the different type of numbers
1.Natural Numbers(N)-1,2,3,4,5,....................

2.Whole Numbers(W)-0  +  Natural numbers means 0,1,2...........

3.Prime Numbers-Prime numbers are those numbers which have only two factors ( 1 and number itself).
For Example:-17 it has only two factors 1 and 17
(Factors of a number(Say T) are the numbers(a,b,c) which divide number(T) perfectly)
2 is the only prime number which is even
All prime numbers (except 2,3) can be expressed in the form of 6k+5 and 6k +1(that is when divided by 6 they will give 1 or 5 as remainder)
However it is important to note that not all numbers of the form 6k-1 and 6k+1 are  prime numbers
Example:25(6k+1) is not a prime number
35(6k-1) is not aprime number
Its just a convinient way to express prime numbers


4.Composite Numbers-are those numbers which have more than two factors like 25,35...
1 is neither prime nor composite


5.Integers(I)-   from -infinity,.............-92,-91,.....................,0,1,2,,...................99,...........upto infinity

6.Real Numbers(R)- from -infinity to infinity

7.Rational Numbers-Rational numbers are numbers which can be expressed in the form of p/q where q is not equal to 0 and  p and q are integers.
Like 3(3/1),7/8,2.6bar.....

8.Irrational numbers -are numbers which cannot be expressed in the form of p/q like sqrt(2),pie