How to round this to the nearest thousand 19,836.2838

The answer is 20,000

19,836.2838 or 19,836 is closer to 20,000 than 19,000 so if you round to the nearest thousands, 20,000 is your answer

Don't let all those numbers worry you. You have 19 thousand and change now. The only question is whether the little stuff is more or less than half of another thousand. Look at the first digit after the 19 thousand. It's an '8'. That's all you need. That '8' tells you that the whole thing is closer to 20 thousand than it is to 19 thousand. So the "nearest thousand" is 20,000.