Which of the following numbers is a perfect square?

Correct Answer: D

Rationale: A perfect square is a number obtained by squaring an integer. In this case, 16 is a perfect square because it is the result of squaring 4 (4 x 4 = 16). The other answer choices, 10, 12, and 15, are not the product of squaring any whole number, making them incorrect. Therefore, the correct answer is 16, as it is a perfect square.

Correct Answer: B

Rationale: To find 70% of 65, you multiply 0.7 by 65. Mathematically, 0.7 * 65 = 45.5. Therefore, the correct answer is 45.5. Choice A (40.5) is incorrect because it is not the result of multiplying 0.7 by 65. Choice C (50) is incorrect as it is higher than the correct answer. Choice D (55) is also higher than the correct result and is therefore incorrect.

Correct Answer: A

Rationale: The correct answer is A: 20.73. To calculate the sum of 9.43 and 11.3, you simply add the two numbers together. Therefore, 9.43 + 11.3 equals 20.73. Choice B (21.3) is incorrect because it represents the sum of rounding the numbers up. Choice C (22) and choice D (19.5) are also incorrect as they do not accurately reflect the sum of the provided numbers.

Correct Answer: A

Rationale: To convert meters to millimeters, you multiply by 1000 since there are 1000 millimeters in 1 meter. Therefore, 5 meters multiplied by 1000 equals 5000 millimeters. Choice A is correct as it represents the accurate conversion from meters to millimeters. Choices B, C, and D are incorrect as they do not provide the correct conversion factor from meters to millimeters.

Correct Answer: B

Rationale: To convert 1906 to Roman numerals, break it down into components: 1000 (M), 900 (CM), 6 (VI), resulting in MCMVI. Therefore, the correct Roman numeral representation for 1906 is MCMVI. Choice A (MCMIV) is incorrect as it represents 1904. Choice C (MDCCCCVI) is incorrect because it uses the subtractive notation incorrectly, and it's considered nonstandard. Choice D (MCMVII) is incorrect as it represents 1907, not 1906.