The telephone book is 2.6 inches thick, with 565 sheets of paper.
What this means is 2.6 inches is the thickness of 565 sheets of paper.
To find the thickness of each sheet of paper, all we do is:
2.6 ÷ 565
This gives us quite a large answer:
0.0046017699
To round to the thousandth place, we look at the third number past the decimal and look to see if we need to round up or round down. The number to the right of our digit in the thousandth place lets us know (in this case) to round up.
Therefore, 0.0046017699 rounded to the nearest thousandth is: