You can round it to the nearest thousand by figuring out whether 347 turns out to be closer to 0 or 1,000. If it's closer to 0, you round to the nearest thousand by producing the result 3,000. Since 347 is closer to 0, it would be incorrect to round the number 3,347 to the nearest thousand by producing the result 4,000.
In this case you round to the nearest thousand by producing the result 3,000.
