∑ DANEMATHICS
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Grade 9 · Whole Numbers
The Real Number System: Rational & Irrational Numbers
MEMORANDUM
Name:
Class:
Date:
Mark
/ 14
Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.
- 1List the natural numbers less than 5.(1)1, 2, 3, 4✓ (1)
- 2What is the only whole number that is not a natural number?(1)0✓ (1)
- 3Is −7 an integer? Is it a natural number?(2)Yes, it is an integer; no, it is not natural.✓✓ (2)
- 4Define a rational number.(2)One that can be written as a/b with a, b integers and b ≠ 0.✓✓ (2)
- 5Is √36 rational or irrational? Why?(2)Rational — √36 = 6, an exact whole number.✓✓ (2)
- 6Is √20 rational or irrational? Why?(2)Irrational — 20 is not a perfect square, so the decimal never ends or repeats.✓✓ (2)
- 7Is 0,45 rational?(1)Yes — it terminates, and equals 45/100.✓ (1)
- 8Is 0,666… rational?(1)Yes — it recurs, and equals 2/3.✓ (1)
- 9Name two irrational numbers.(2)π and √2 (or the square root of any positive whole number that is not a perfect square)✓✓ (2)
TOTAL: 14 marks