ACT Preparation / Unit 7 ACT 0601 short lesson, about 20 seconds
The Real Number System
Captions available
The idea
The natural numbers are 1, 2, 3 and so on; adding 0 gives the whole numbers; adding the negatives gives the integers. Every integer is rational, and the rationals and irrationals together make the real numbers.
In practice
−4 is an integer and rational, but not whole.
Where people slip
The sets nest: a natural number belongs to every larger set.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
- Nothing. This is a starting point.
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