"The next step is to select a random number between 0 and 100. To do this, the program takes the last three digits of the certificate number and inverts them into a number with one decimal place. In this particular example, the last three digits are 433, which inverted yield 33.4. Since 33.4 lies between 0 and 60, White is chosen as the main race for this case.”
http://www.cdc.gov/nchs/data/dvs/Multiple_race_docu_5-10-04.pdf