Math Number Sense and Operations — Questions and Answers
Question 1: Evaluate: 3 + 4 × 2 − 1
Correct answer: 10
Following order of operations (PEMDAS), multiplication is performed first: 4 × 2 = 8, then left to right: 3 + 8 − 1 = 10.
Question 2: Which property is illustrated by: 5 × (3 + 4) = 5 × 3 + 5 × 4?
- Commutative Property
- Associative Property
- Distributive Property (Correct answer)
- Identity Property
Correct answer: Distributive Property
The Distributive Property states that a(b + c) = ab + ac, which is exactly what is shown here.
Question 3: What is the absolute value of −17?
- −17
- 17 (Correct answer)
- 1/17
- 0
Correct answer: 17
Absolute value represents the distance from zero on the number line, so |−17| = 17.
Question 4: Which of the following is a prime number?
Correct answer: 53
53 is prime because it has no divisors other than 1 and itself; 51 = 3 × 17, 57 = 3 × 19, and 1 is not prime by definition.
Question 5: What is the least common multiple (LCM) of 6 and 8?
Correct answer: 24
Since 6 = 2 × 3 and 8 = 2³, the LCM = 2³ × 3 = 24.
Question 6: Evaluate: (−3) × (−4) + (−2)
- −14
- 10 (Correct answer)
- 14
- −10
Correct answer: 10
Two negatives multiplied give a positive: (−3) × (−4) = 12, then 12 + (−2) = 10.
Question 7: What is 2⁵?
- 10
- 25
- 32 (Correct answer)
- 64
Correct answer: 32
2⁵ means 2 multiplied by itself 5 times: 2 × 2 × 2 × 2 × 2 = 32.
Question 8: 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 9: 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 10: 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 11: What is √144?
- 11
- 12 (Correct answer)
- 13
- 14
Correct answer: 12
12 × 12 = 144, so the square root of 144 is 12.
Question 12: 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 13: 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 14: 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.
Question 15: What is 3/4 + 5/6?
- 8/10
- 19/12 (Correct answer)
- 8/24
- 4/5
Correct answer: 19/12
Converting to a common denominator of 12: 3/4 = 9/12 and 5/6 = 10/12, so 9/12 + 10/12 = 19/12.
Question 16: What is 15% of 80?
- 10
- 12 (Correct answer)
- 14
- 15
Correct answer: 12
15% of 80 = 0.15 × 80 = 12.
Question 17: The ratio of boys to girls in a class is 3:5. If there are 24 boys, how many girls are there?
Correct answer: 40
Since 24 boys corresponds to 3 parts, one part = 8; 5 parts (girls) = 5 × 8 = 40.
Question 18: In the number 5,847,392, what is the place value of the digit 4?
- Thousands
- Ten-thousands (Correct answer)
- Hundred-thousands
- Hundreds
Correct answer: Ten-thousands
Reading from right to left: ones, tens, hundreds, thousands, ten-thousands — the digit 4 sits in the ten-thousands place.
Question 19: Evaluate: −8 + 15 − 3
Correct answer: 4
−8 + 15 = 7, then 7 − 3 = 4.
Question 20: Which fraction is equivalent to 0.625?
- 3/4
- 5/8 (Correct answer)
- 2/3
- 7/10
Correct answer: 5/8
0.625 = 625/1000; simplifying by dividing numerator and denominator by 125 gives 5/8.
Question 21: Which of the following is NOT an integer?
- −5
- 0
- 3/1
- 1/3 (Correct answer)
Correct answer: 1/3
1/3 = 0.333… is a repeating decimal and cannot be expressed as a whole number, so it is not an integer.