1. Write √72 in the form a√2.
- A6√2
- B36√2
- C3√2
- D12√2
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Answer: A. 72 = 36 × 2, so √72 = √36 × √2 = 6√2. The 36 must be square-rooted when it comes out of the root.
By Team Megalecture · Updated 4 Nov 2026
46 exam-style questions on Number, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
46 questions · 5 topics · 10 per test
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
Answer: A. 72 = 36 × 2, so √72 = √36 × √2 = 6√2. The 36 must be square-rooted when it comes out of the root.
Answer: C. Multiply top and bottom by 3 + √5: the denominator becomes 9 − 5 = 4, so 4(3 + √5)/4 = 3 + √5. Using 9 + 5 in the denominator is the common slip.
Answer: D. Bina gets 5/7, so Ali : Bina = 2/7 : 5/7 = 2 : 5. 2 : 7 compares Ali with the total.
Answer: A. 360 = 8 × 45 = 23 × 32 × 5. 10 and 45 are not prime, and 22 × 33 × 5 = 540.
Answer: A. 2/3 = 0.666…, which is less than 0.67. −5 is below −3, 0.6 equals 3/5, and a square is never negative.
Answer: D. This is a difference of two squares: 32 − (√5)2 = 9 − 5 = 4. The middle terms +3√5 and −3√5 cancel.
Answer: D. Next time together is the LCM of 12 and 18, which is 36 minutes, so 9:36 am. 6 is the HCF, and 12 × 18 = 216 is a common multiple but not the lowest.
Answer: A. Let x = 0.444…; then 10x = 4.444…, so 9x = 4 and x = 4/9. 4/10 is only 0.4, which stops.
Answer: A. 4 × 6 = 24 and 105 × 10−2 = 103, so 24 × 103 = 2.4 × 104. 24 × 103 is the right value but not standard form, because 24 is not between 1 and 10.
Answer: B. Take the fourth root first: 4√16 = 2, then cube: 23 = 8. 12 comes from multiplying 16 by 3/4.
46, each with the answer and a short explanation, across 5 topics: N1–N5 Structure and calculation, N6–N7, N9 Powers, roots, indices and standard form, N8 Surds and exact calculation, N10–N12 Fractions, decimals and percentages, N13–N16 Measures, estimation and bounds. Every chapter test draws ten of them, so you can take it many times.
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The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.