Number Systems

Question 1

Natural numbers (ℕ)

Answer 1

Typically start from 1 (or 0, depending on the definition) and include all positive whole numbers.

Question 2

Integers (ℤ)

Answer 2

Include positive and negative whole numbers, as well as zero.

Question 3

Rational numbers (ℚ)

Answer 3

Numbers that can be written as a fraction a/b, where a and b are integers and b != 0.

Question 4

Irrational numbers

Answer 4

Numbers that cannot be expressed as a fraction, like 𝜋 or sqrt2, with non-repeating, non-terminating decimal expansions.

Question 5

Real numbers (ℝ)

Answer 5

Include all rational and irrational numbers, representing any point on the number line.

Question 6

Complex numbers (ℂ)

Answer 6

Include numbers of the form
𝑎 + 𝑏𝑖, where 𝑎 and 𝑏 are real, and 𝑖 is the imaginary unit.