Number system : A study about the characteristics of different numbers is called a number system.  Different types of numbers       1) Natural Numbers       2) Whole Numbers       3) Integers           (a) Positive Integers b) Negative Integers c) Non-Positive Integers d) Non Negative Integers )      4) Rational Numbers       5) Irrational Numbers       6) Real Numbers       7) Imaginary Numbers       8) Even Numbers       9) Odd Numbers       10) Prime Numbers       11) Composite Numbers       12) Co - Prime  Number (1) Natural Numbers :     Counting numbers are called natural numbers. Set of Natural numbers denoted by N Example       N=`{1,2,3,4,5,........ }`      Note -      Zero `(0)` is not a natural number (2) Whole Numbers      All counting numbers with zero (0) are  called whole numbers, set of Whole numbers denoted by W Example      W=`{0,1,2,3,4.........}`                     Note -      Zero `(0)` is the whole number. (3) Integers:      All-natural numbers, `0` and negatives