How do you round off to leave one nonzero digit of 6 592?

1. Look at the first digit after the first non-zero digit;
2. if it is 5 or more, add one to the first digit, otherwise keep the first digit as it is;
3. replace all the digits after the first digit by 0s.

6592:

1. First digit is 6, first digit after it is 5
2. is 5 greater than or equal to 5 - yes, so add 1 to the first digit: 6 + 1 = 7
3. replace the 592 by 000, to give 7000