Prime numbers? Select ALL.
- A. 21
- B. 23
- C. 25
- D. 27
- E. 29
Correct Answer & Rationale
Correct Answer: B,E
Prime numbers are defined as natural numbers greater than 1 that have no positive divisors other than 1 and themselves. - **Option A: 21** is not prime because it can be divided by 1, 3, 7, and 21. - **Option B: 23** is prime; it has no divisors other than 1 and 23. - **Option C: 25** is not prime as it can be divided by 1, 5, and 25. - **Option D: 27** is not prime since it can be divided by 1, 3, 9, and 27. - **Option E: 29** is prime; it has no divisors other than 1 and 29. Thus, 23 and 29 are the only prime numbers in the list.
Prime numbers are defined as natural numbers greater than 1 that have no positive divisors other than 1 and themselves. - **Option A: 21** is not prime because it can be divided by 1, 3, 7, and 21. - **Option B: 23** is prime; it has no divisors other than 1 and 23. - **Option C: 25** is not prime as it can be divided by 1, 5, and 25. - **Option D: 27** is not prime since it can be divided by 1, 3, 9, and 27. - **Option E: 29** is prime; it has no divisors other than 1 and 29. Thus, 23 and 29 are the only prime numbers in the list.
Other Related Questions
Driveway for two cars, width?
- A. 0.7
- B. 7
- C. 70
- D. 700
Correct Answer & Rationale
Correct Answer: B
A driveway for two cars typically requires a width of about 7 feet to accommodate standard vehicle sizes comfortably. Option A (0.7) is too narrow, as it would not allow even one car to fit. Option C (70) and Option D (700) are excessively wide for a residential driveway, making them impractical and unnecessary. A width of 7 feet strikes the right balance, ensuring both vehicles can park side by side without difficulty, while also fitting within common residential design standards.
A driveway for two cars typically requires a width of about 7 feet to accommodate standard vehicle sizes comfortably. Option A (0.7) is too narrow, as it would not allow even one car to fit. Option C (70) and Option D (700) are excessively wide for a residential driveway, making them impractical and unnecessary. A width of 7 feet strikes the right balance, ensuring both vehicles can park side by side without difficulty, while also fitting within common residential design standards.
178-degree angle?
- A. Acute
- B. Obtuse
- C. Right
- D. Straight
Correct Answer & Rationale
Correct Answer: B
An angle measuring 178 degrees is classified as obtuse, as it is greater than 90 degrees but less than 180 degrees. Option A, acute, refers to angles less than 90 degrees, which does not apply here. Option C, right, denotes a 90-degree angle, clearly not fitting for 178 degrees. Option D, straight, describes a 180-degree angle, which is also not applicable since 178 degrees is slightly less than that. Thus, the only suitable classification for a 178-degree angle is obtuse.
An angle measuring 178 degrees is classified as obtuse, as it is greater than 90 degrees but less than 180 degrees. Option A, acute, refers to angles less than 90 degrees, which does not apply here. Option C, right, denotes a 90-degree angle, clearly not fitting for 178 degrees. Option D, straight, describes a 180-degree angle, which is also not applicable since 178 degrees is slightly less than that. Thus, the only suitable classification for a 178-degree angle is obtuse.
Which would be read as 'two million three hundred six thousand nine hundred thirty-four'?
- A. 2,036,934
- B. 2,306,934
- C. 2,360,934
- D. 2,369.03
Correct Answer & Rationale
Correct Answer: B
Option B, 2,306,934, accurately represents 'two million three hundred six thousand nine hundred thirty-four.' The number is broken down as follows: 2 million (2,000,000), 300 thousand (300,000), 6 thousand (6,000), 900 (900), and 30 (30), culminating in 2,306,934. Option A, 2,036,934, incorrectly includes only 30 thousand instead of 300 thousand. Option C, 2,360,934, misplaces the hundreds, showing 360 thousand instead of 306 thousand. Option D, 2,369.03, is not a whole number representation and introduces decimal values, which are irrelevant in this context.
Option B, 2,306,934, accurately represents 'two million three hundred six thousand nine hundred thirty-four.' The number is broken down as follows: 2 million (2,000,000), 300 thousand (300,000), 6 thousand (6,000), 900 (900), and 30 (30), culminating in 2,306,934. Option A, 2,036,934, incorrectly includes only 30 thousand instead of 300 thousand. Option C, 2,360,934, misplaces the hundreds, showing 360 thousand instead of 306 thousand. Option D, 2,369.03, is not a whole number representation and introduces decimal values, which are irrelevant in this context.
Quickly multiply 24x16?
- A. 20x20-4x4
- B. 20x20
- C. 20x10+4x6
- D. 25x10+4x15
Correct Answer & Rationale
Correct Answer: A
Option A, 20x20 - 4x4, effectively utilizes the difference of squares method. It simplifies the multiplication by recognizing that 24 can be expressed as 20 + 4 and 16 as 20 - 4, leading to a calculation of (20+4)(20-4). Option B, 20x20, underestimates the value of 24 and 16, yielding only 400 instead of the correct 384. Option C, 20x10 + 4x6, inaccurately breaks down the multiplication, leading to 200 + 24, which totals 224. Option D, 25x10 + 4x15, misrepresents the factors, resulting in 250 + 60, totaling 310. Thus, option A is the most accurate approach for this multiplication.
Option A, 20x20 - 4x4, effectively utilizes the difference of squares method. It simplifies the multiplication by recognizing that 24 can be expressed as 20 + 4 and 16 as 20 - 4, leading to a calculation of (20+4)(20-4). Option B, 20x20, underestimates the value of 24 and 16, yielding only 400 instead of the correct 384. Option C, 20x10 + 4x6, inaccurately breaks down the multiplication, leading to 200 + 24, which totals 224. Option D, 25x10 + 4x15, misrepresents the factors, resulting in 250 + 60, totaling 310. Thus, option A is the most accurate approach for this multiplication.