Voltage dividers that divide by 10, or 100, or 1,000 are tough with standard resistors. The numbers do not come out exactly with standard resistors. By adding one resistor to the divider it is possible to get the division ratio exact (not counting resistor tolerances). And except for the "bottom" two resistors the upper resistors in the divider are very often in stock in your shop. Values like 1.00 K, 10.00 K, 100.0 K. Note that the resistor tolerance for all the resistors should be .1%. If you don't need on the order of .1% divider accuracy you don't need this divider.