Numbers nest inside larger families — naturals ⊂ integers ⊂ rationals ⊂ reals ⊂ complex.
Quick check
What is the SMALLEST standard set that contains −5?
The families
- ℕ Natural — 1, 2, 3, …
- ℤ Integer — …, −1, 0, 1, …
- ℚ Rational — fractions a/b.
- ℝ Real — decimals, including irrationals.
- ℂ Complex — a + bi.