Rounded numbers are easier to work with in your head. They are only approximate.
An exact answer can not be obtained with these numbers. Sometimes an exact answer
is not required.

To round numbers to the nearest ten thousand, make the numbers whose last four digits
are 0001 through 4999 into the next lower number that ends in 0000. For example 54,424
rounded to the nearest ten thousand would be 50,000. Numbers that have the last
four digits of 5000 or more should be rounded up to the next even ten thousand.
The number 78,988 rounded to the nearest ten thousand would be 80,000.