Math Number Sense and Operations 2 — Questions and Answers
Question 1: Which number is written in correct scientific notation?
- 23.5 × 10³
- 2.35 × 10⁴ (Correct answer)
- 0.235 × 10⁵
- 235 × 10²
Correct answer: 2.35 × 10⁴
Scientific notation requires the coefficient to be at least 1 and less than 10; 2.35 × 10⁴ = 23,500 and satisfies this condition.
Question 2: Which of the following numbers is divisible by 9?
- 245
- 432 (Correct answer)
- 361
- 127
Correct answer: 432
A number is divisible by 9 if the sum of its digits is divisible by 9; for 432: 4 + 3 + 2 = 9.
Question 3: What is the greatest common factor (GCF) of 36 and 48?
- 6
- 12 (Correct answer)
- 18
- 144
Correct answer: 12
36 = 2² × 3² and 48 = 2⁴ × 3, so GCF = 2² × 3 = 12.
Question 4: What is √144?
- 11
- 12 (Correct answer)
- 13
- 14
Correct answer: 12
12 × 12 = 144, so the square root of 144 is 12.
Question 5: Which of the following is an irrational number?
- 0.333…
- √16
- √5 (Correct answer)
- 7/3
Correct answer: √5
√5 ≈ 2.2360679… is a non-terminating, non-repeating decimal and cannot be expressed as a fraction, making it irrational.
Question 6: Which list correctly orders −3, 0.5, −1.2, and 2 from least to greatest?
- −3, −1.2, 0.5, 2 (Correct answer)
- −1.2, −3, 0.5, 2
- 2, 0.5, −1.2, −3
- 0.5, −1.2, 2, −3
Correct answer: −3, −1.2, 0.5, 2
On the number line, −3 < −1.2 < 0.5 < 2, so the correct order is −3, −1.2, 0.5, 2.
Question 7: Round 3,847 to the nearest hundred.
- 3,800 (Correct answer)
- 3,850
- 3,900
- 4,000
Correct answer: 3,800
The tens digit is 4 (less than 5), so the hundreds digit stays at 8 and the number rounds down to 3,800.
Math Number Sense and Operations 2
Which number is written in correct scientific notation?