To round to 3 decimal places, look at the 4th decimal digit.<br><br>
&bull; 86.54545 &mdash; the 3rd decimal is 5, the 4th is 4.<br>
&bull; Since the 4th digit is less than 5, keep the 3rd digit unchanged.<br>
&bull; Drop all digits after the 3rd decimal.<br>
<br>
Final Answer: 86.545