0.387123
Note the place value of each digit
0
.
3 (tenths)
8 (hundredths)
7 (thousandths)
1 (ten thousandths)
2 (hundred thousandths)
3 (millionths)
to find the nearest thousandths, look at the place value of the ten thousandths. It is a 1. Because it is less than 5, you round down.
0.387123 becomes 0.387
0.387 is your answer
hope this helps