That means that there are 3 digits after the decimal point (or comma - some countries use a comma to separate decimals).
It is: 0.389 rounded to 3 decimal places
6325
0.071
Move decimal 3 places to the left 126/1000 = 0.126
17.635 already is rounded to 3 decimal places.
0.044051 to 3 decimal places is 0.0441
It is: 4729.412 rounded to 3 decimal places
318
It is: 9 and 25/60 = 9.417 hours rounded to 3 decimal places
It is 87.656 when rounded to 3 decimal places
It is 3.540 rounded to 3 decimal places
85 rounded to three decimal places is 85.000