it simpler if u don want to remember tables.

u multiply the (HTT/ram) ratio -inverse of ram:htt ratio in the bioses- with the
cpu multiplier , and u aproximate to its closer bigger integer.that's ur memory divider,then u divide ur cpu mhz by this divider..

example if multi is 8 ,HTT=240(=>cpu=1920MHZ) and divider "ram:htt" is 5:6 , u multiply 8*(6/5)=9.6 , then approximate to the bigger closer integer =.. 10 and divide the cpu clock by ths number ...=> ram clock is 1920/10=192mhz

of course if u choose a half multi , the bios "approximates" it to the closest integer(bigger)