Ummmm, the LEDs are arranged in parallel on the die.
I suspect it is nomenclature that is tripping you up. When dealing with power leds it is common to refer to the parts making up the LED on a macroscopic level as below.
(Note that I've rotated the actual direction of the strings by 90 degrees if you look closely you can actually see the bond wires in the LED form the series strings vertically)
As I hope you can see on this type of LED there are 10 strings of 10 DIE in series on this common type of power led. As I do not have to explain, devices in series pass the same current through them all, and in parallel the current divides, therefore each die sees 10% of the total current through the LED and 100% of the current through it's series string.
Each die has a forward voltage of around 3.3v, and has a typical forward current of around 300mA (not 20mA like you have said).
Each die therefore has a consumption of 3.3v * 0.3A = 0.99W
Each string therefore has a consumption of 33v * 0.3A = 9.9W
And the led therefore has a consumption of 33v * 3A = 99W