ummmm.... I guess 831. No offense, but do you know how to do subtraction?
idk since 1 in 1000 is the first sig fig, the final answer would therefore round to the thousands, so 831.136 should round off to 1000.
but, using online sig fig calculators (first few that pops up when googling "sig fig calculators"), the answer comes off as 831.
not sure if the calculators are correct or incorrect in this case.