# Important for Mathematics Basics: Types of Numbers: Natural and Whole Numbers

Get unlimited access to the best preparation resource for IAS : Get detailed illustrated notes covering entire syllabus: point-by-point for high retention.

I. Natural Numbers: Counting numbers I, 2.3,4, 5, … are called natural artillery.

2. Whole Numbers: All counting numbers together with zero form the set of whole number. Thus,

(A) 0 is the only whole number which is not a natural number.

(B) Every natural number is a whole number

3. Integers: All-natural numbers. 0 and negatives of counting numbers i.e.. - 3, - 2, - 1.0.

I. 2,3 … together form the set of integers

(A) Positive Integers t 11.2. 3,4, … I is the set of all positive integers.

(B) Negative Integers: (- I, - 2, - 3 … I am the set of all negative integers.

(C) Non-Positive and Non-Negative integers: 0 is neither positive nor negative.

So, 0,1, 2,3 … I represent the set of non-negative integers, while (0, - I, - 2, - 3) represents the set of non-positive integers.

4. Even Numbers: A number divisible by 2 is called an over, number. e. g. 2.4. 6,8.10. etc

5. Odd Numbers: A number not divisible by 2 is called an odd number. es, 1.3. 5, 7,9, 11, etc.

6. Prime Numbers: A number greater than 1 is called a prime number, if it has exactly two factors namely 1 and the number itself.

Prime lumbers up to 100 are . 2,3, 5,7. II, 13.17. 19.23. 29.31,37.41, 43, 47, 53, 59, 81,87, 71.73, 79, 83,89, 97.

7. Composite Numbers: Numbers greater than 1 which are not prime, are known OS composite numbers. e. g. , 4.6. 8.9,10.12.

Note: (1) 1 as neither prime nor composite.

(ii) 2 is the only even number which is prime.

(iii) There are 25 prime numbers between 1 and 100.

8. Co-primes prime numbers a and b are said to be co primes. if their H. C. F. is 1.

e. g. (2,3) , (4.5) . (7,9) , (8.11) . etc. are co-primes.

sbi po preparation continues …