Luis and his family flew 51,487 miles last summer while on vacation rounded to the nearest thousand how many miles did they fly?

 Luis and his family flew 51 487 miles. This needs to be rounded to the nearest thousands to know how many miles did Luis and his family flew?
=> 51 487 = where 5 ten thousands, 1 thousands, 4 hundreds, 8 tens and 7 ones.
=> 51 487 = 50 000 + 1 000 + 400 + 80 + 7
=> Round to the nearest thousands. The thousands value is 1, and the number next to thousands is 4, which is below 5. SO we need to round down.
=> 51 000 miles.