Chapter 1 - Problem Solving and Critical Thinking - 1.2 Estimation, Graphs, and Mathematical Models - Exercise Set 1.2 - Page 26: 3

e = 2.718

e $\approx$ 2.718281828459045 To round the value of e to the nearest thousandth, we see the digit next to the thousandth place, which is 2 and it is lesser than 5, so the thousandth place digit remains the same and the other digit after it is neglected. The round off value to the nearest thousandth is e = 2.718.