16,000 miles.
You need to round up from the hundreds.
As a rule of thumb, if the number after the number you're rounding is above 5, round up; if not, round down.
Like if I was rounding to tens:
38 rounds up to 40
34 rounds down to 30.
Anyways, in this case, then, we round 15680 up to 16000 miles.
