Correct Answer: C

Rationale: 1 kilometer equals 1,000 meters. Therefore, 2 kilometers equals 2,000 meters. Choice A, 100 meters, is incorrect as it represents only 1/10th of a kilometer. Choice B, 200 meters, is incorrect as it represents only 1/5th of a kilometer. Choice D, 3000 meters, is incorrect as it miscalculates the conversion from kilometers to meters.

Correct Answer: A

Rationale: To convert grams to milligrams, you need to multiply by 1,000 since there are 1,000 milligrams in a gram. So, 1,000 x 7 grams = 7,000 mg. This means that there are 7,000 milligrams in 7 grams. Choices B, C, and D are incorrect because they do not correctly convert grams to milligrams.

Correct Answer: C

Rationale: Rationale: The correct answer is obtained by applying the formula for the circumference of a circle, which is \(C = \pi \times d\), where \(d\) is the diameter of the circle. By substituting the given diameter of 40cm into the formula and performing the calculation, we find that the circumference of the pizza is 125.6cm.

Correct Answer: C

Rationale: To calculate the total number of words typed in 20 minutes, multiply the typing speed per minute (45 words) by the duration in minutes (20 minutes): 45 words/min 20 min = 900 words. Therefore, the correct answer is 900 words. Choices A, B, and D are incorrect because they do not reflect the accurate calculation based on the given information.

Correct Answer: A

Rationale: To calculate 54% of $789.56, you multiply 0.54 by 789.56, which equals $426.36. Therefore, choice A, $426.36, is the correct answer. Choice B, $426.37, is incorrect as it is a slightly higher value. Choice C, $363.20, is incorrect as it is significantly lower than the correct answer. Choice D, $526.38, is incorrect as it is higher than the correct calculation result.