Final answer:
When rounding the number 531 to one significant figure, it becomes 500. The first non-zero digit is a 5 and the trailing zeros serve as placeholders to show the magnitude.
Step-by-step explanation:
The question 'What is 531 to one significant figure?' pertains to the concept of significant figures in mathematics. When rounding to one significant figure, we look at the first non-zero digit and consider the digit immediately to its right. In the number 531, the first non-zero digit is 5. Since the number immediately following the 5 is a 3, we do not round up the 5. Therefore, 531 rounded to one significant figure is 500. It's important to note that the trailing zeros are considered placeholders to indicate the magnitude of the number.