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Question 551421: Is -12 a real, rational or irrational number?
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! Real numbers are all the numbers that we use for real measurements. (That's not an official definition, but may help you understand what "real number" means).
Real numbers include all integers, like, 2, 0, and -12.
Real numbers include all RATIOnal numbers that can be expressed as RATIOs of two integers, like 3/4, -5/7, 2, 0, and -12. (Some of those rational numbers are integers; the others are what you used to call fractions).
Real numbers also include numbers that are not rational, but are real anyway, like  , and  . We know is real because it's the length of the circumference of a circle with a diameter measuring  . We know is real because it's the length of the diagonal of a square with sides measuring 1. We cannot express or as fractions (rational numbers), or a decimal number that end or repeat, like  =0.28, or  =0.0833333.... . The best we can do with irrational numbers is write approximations like 3.14, or 3.142, or 3.1416, or 3.14159 for , but there is no rhyme or reason to what the next digit will be.
The number -12 is definitely real. Sometimes that's been the temperature outside; it was really cold. It is also a rational number, and it is also an integer. It is not an irrational number.
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