01 Key Concepts
Natural Numbers
Counting numbers starting from 1: 1, 2, 3, 4, 5, ... (do not include 0 or negatives).
Whole Numbers
Natural numbers plus zero: 0, 1, 2, 3, 4, ...
Integers
Whole numbers plus their negatives: ..., -3, -2, -1, 0, 1, 2, 3, ...
Rational Numbers
Any number that can be written as a fraction a/b, where b is not 0. Examples: 1/2, -3/4, 5 (since 5 = 5/1).
Even and Odd Numbers
Even numbers are exactly divisible by 2 (2, 4, 6...). Odd numbers are not (1, 3, 5...).
Prime and Composite Numbers
A prime number has exactly two factors: 1 and itself (2, 3, 5, 7...). A composite number has more than two factors (4, 6, 8, 9...).
02 Solved Examples
Example 1 Classify -7, 0, 4, and 2/3 as natural, whole, integer, or rational.
- -7 is negative, so it's an integer and a rational number (not natural or whole).
- 0 is a whole number and a rational number (not natural).
- 4 is a natural number, whole number, integer, and rational number.
- 2/3 is a rational number only (it is not a whole number).
Answer: -7: integer, rational | 0: whole, rational | 4: natural, whole, integer, rational | 2/3: rational
Example 2 Is 17 a prime number?
- Check if 17 is divisible by any number other than 1 and 17.
- It is not divisible by 2, 3, 5 (the only primes less than its square root, ~4.1).
- Since no smaller number divides it evenly, 17 has only two factors: 1 and 17.
Answer: Yes, 17 is prime.
Example 3 List all even numbers between 10 and 20.
- Even numbers are divisible by 2.
- Starting after 10: 12, 14, 16, 18.
Answer: 12, 14, 16, 18
03 Practice Questions
1Is -5 a whole number?
No — whole numbers cannot be negative.
2Give an example of a composite number between 1 and 10.
4, 6, 8, or 9
3Is 0 a natural number?
No, but it is a whole number.
4Write 3 as a fraction to show it is rational.
3/1
5Is 21 prime or composite?
Composite (3 x 7 = 21)
📄 Numbers — Downloadable Worksheet
10 questions with a full answer key. Grab the PDF to print, or try the interactive version in your browser.