. Ordered Pair Observe the seating plan in an auditorium (Fig. . ).
To help orderly occupation of seats, tokens with numbers such as ( , ), ( , ), ( , ), ( , ) etc. are issued. The person who gets ( , ) will go to row and occupy the th seat. Thus the first number denotes the row and the second number, the seat.
Which seat will the visitor with token ( , ) occupy? Can he go to th row and take the th seat? Do ( , ) and ( , ) refer to the same location? No, certainly!
What can you say about the tokens ( , ), ( , ) and ( , )? This is one example where a pair of numbers, written in a particular order, precisely indicates a location. Such a number pair is called an ordered pair of numbers. This notion is skillfully used to mathematize the concept of a “Relation”.