A complex number such as 5+2i is made up of two parts, a real part 5, and an imaginary part 2. The imaginary part is the multiple of i. It is common practice to use the letter z to stand for a complex number and write z = a + bi where a is the real part and b is the imaginary part.

What is an example of a non real number?

A non-real, or imaginary, number is any number that, when multiplied by itself, produces a negative number. Mathematicians use the letter “i” to symbolize the square root of -1. An imaginary number is any real number multiplied by i. For example, 5i is imaginary; the square of 5i is -25.

## What are the real numbers?

In mathematics, a real number is a value of a continuous quantity that can represent a distance along a line. The real numbers include all the rational numbers, such as the integer −5 and the fraction 4/3, and all the irrational numbers, such as √2 (1.41421356, the square root of 2, an irrational algebraic number).

## Are the real numbers a subset of the complex numbers?

If you square a real number you always get a positive, or zero, result. A combination of a real and an imaginary number in the form a + bi, where a and b are real, and i is imaginary. The values a and b can be zero, so the set of real numbers and the set of imaginary numbers are subsets of the set of complex numbers.

## What are the common numbers?

The low numbers (0, 1, 2) are probably the most common and the single-digit numbers are all among the most common, but how common are larger numbers and which larger numbers are the most common? Lower numbers tend to be smaller, as do round numbers like 50, 25, and 40.