Home Practice
For learners and parents For teachers and schools
Textbooks
Full catalogue
Leaderboards
Learners Leaderboard Classes/Grades Leaderboard Schools Leaderboard
Pricing Support
Help centre Contact us
Log in

We think you are located in United States. Is this correct?

1.2 The real number system

Test yourself now

High marks in science are the key to your success and future plans. Test yourself and learn more on Siyavula Practice.

Sign up and test yourself

1.2 The real number system (EMA3)

6a0ce429c29cab84a1b198dedec2c2a1.png

We use the following definitions:

  • \(\mathbb{N}\): natural numbers are \(\left\{1; 2; 3; \ldots\right\}\)

  • \(\mathbb{N}_0\): whole numbers are \(\left\{0; 1; 2; 3; \ldots\right\}\)

  • \(\mathbb{Z}\): integers are \(\left\{\ldots; -3; -2; -1; 0; 1; 2; 3; \ldots\right\}\)

The following video shows an example of determining which of the above sets of numbers a particular number is in.

Video: 2DBH

Not all numbers are real numbers. The square root of a negative number is called a non-real or imaginary number. For example \(\sqrt{-1}\), \(\sqrt{-28}\) and \(\sqrt{-5}\) are all non-real numbers.