The correct answer is: 4
Explanation:
In order to round to 1 significant figure, ALWAYS REMEMBER, we will look at the first digit of the number, and make sure that it is not zero (zero case will be discussed at the end, as in this particular example zero is not the first digit).
In 4.31, the first digit is at unit place is 4. Now you have to decide whether 4.31 is closer to 4 or 5. Indeed, 4.31 is closer to 4. Therefore, 4.31 is rounded off to one significant figure as 4.
(EXTRA INFORMATION) Zero case:
If we have the following number: 0.951. Now the first digit is 0, but as there is a decimal point after that, therefore, it is insignificant. We will move on to the first digit after the decimal point, which is 9 in this case. Now, we will look at the next number. In this case it is 5, therefore, 0.951 is closer to 1.0 after rounding off. Hence, in this case the answer will be 1.0.
