A quarter of a century in airlines and counting, all I've ever needed is fifth-form physics and the three times table.
I figured CX guys use the 4 x tables for their descent profile?
It's really rubbed off on approach controllers in HKG too; I know I'm on profile when I'm asked in a panicked voice if I have enough track miles to land- if I'm at 6000 ft slowed up behind a CX jet, 3 x 6 equals 18 and that's plenty!