6,000
Step-by-step explanation:
To round to the nearest thousand, you keep the digit in the thousands and round up or down, clearing all other smaller units. You round up when the next largest digit, in this case, the hundreds, is 5 or larger. Meanwhile, you round down when it is 4 or smaller. Here it is 1, so you round down to 6,000. If it was 5 or larger, you would round up to 7,000.