Whole Numbers
There are situations in which Natural Numbers are not enough :
 When the temperature is zero or below zero


 When I go to the car park under my building: 

 When I have no money or I owe money to someone: 
In these situations, we need the negative numbers and zero: 5, 4, 3, 2, 1, 0
Then, when we add the zero and the negative numbers to the Natural Numbers, we obtain the Whole Numbers.
We name these numbers with
Z = {... 4, 3, 2, 1, 0, 1, 2, 3, 4,...}
and represent them in a straight line:
Exercises:
1. Associate a Whole Number to these sentences:
a) The temperature is 5 degrees below zero.
b) I live in the sixth floor.
c) I park my car in the second floor of the parking under my building.
2. Represent these numbers in the line: 3, 5, 7, 0, 11
Solutions: 1. a) 5; b) 6; c) 2
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