398.574986215 to the nearest ten-thousandth.

Step-by-step explanation:

It is important to remember that the fourth digit after the decimal point is in the ten-thousandth place.

Then, given the  following number:

You can follow these steps in order ti round it to the nearest ten-thousandth:

1. You can identify that the digit in the ten-thousandth place is:

2. Identify the digit to the right of . This is:

3. Since:

 You must round up. Increase the digit by 1. (Notice that , then the digit to the left of   increases by 1 too). Then: