Answer :

so sig figs are non zero figs and also not in front of decimal so

800=1 sig fig, 8
but
800.0 has 3: 8, 0,0 because there is a decimal and to the left of decimal, all is counted
 so

863
had no decimal so I would round the top number (8)
look at number to right (6) is more than 5 so
round up
900 with out decimal is answer

The correct answer is: 900

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 863, the first digit at hundredth place is 8. Now we will look at the next digit. In this case, the next digit is 6, which is greater than 5, therefore, the 8 (first digit) will round off to 9, and rest of the digits will become zero to round it off to one significant figure. Hence, the answer is 900.

(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.