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Number System ( Basics )

NUMBER SYSTEM



TYPES OF NUMBERS

1. Natural Numbers: Numbers starting from 1, 2, 3, .......... are Natural Numbers.

2. Whole Numbers : Numbers starting from 0, 1, 2, 3, .......... are Whole Numbers. 

3. Integers : Negative, Zero and Positive Numbers comes in category of Intergers. 

     Ex. : -3, -2, -1, 0, 1, 2, 3, etc.

4. Negative Numbers : Numbers like -1, -2, -3, -4 ......... are Negative numbers

5. Positive Numbers : Numbers like 1, 2, 3, 4, .....are Positive Numbers.

6. Rational Numbers : Numbers that are being expressed in the form of p/q.

7. Irrational Numbers : An infinite Non-Recurring , Non - Terminating Decimal Number . Such numbers can't be expressed in the form of p/q.

8. Even Numbers : Numbers that are divisible by 2.

9. Odd Numbers : Numbers that can't be divisible by 2.

10. Prime Numbers : Numbers that are divisible by 1 or itself.   

 NOTE : 2 is only even prime number.
              There are 25 prime numbers upto 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)

11. Co- Prime Numbers : Pair of numbers are considered to be prime if their H. C. F. is 1. 

       Ex.:  5 and 12 are co - prime to each other.
             Consecutive Numbers are co-prime pairs.
             All prime numbers are co-prime pairs.

12. Composite Numbers : Numbers having factors other than itself and 1.

       NOTE : 1 is neither a composite number nor a prime number.

13. Real Numbers : Natural Numbers, Integers, Whole Numbers, Rational Numbers and Irrational Numbers constitutes set of Real Numbers. 

14. Perfect Numbers :  If sum of all the factors of a number excluding itself is equal to the number 

      Ex.:  6 is the first perfect number.  (1 + 2+3)
       Next three perfect Numbers are 28, 496, and 8128

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