In order to round numbers we look at the number to the right of whatever we are rounding to. So in this case we are rounding to the nearest thousand so we look at the number to the right of the thousands which is the hundred in this case. If that number is a 1-4 we round down and if that number is a 5-9 we round up. In this case the number to the right is a 9 so we will round up. The nearest thousand above 9991 is 10,000 so that is what we will round to
