https://en.wikipedia.org/wiki/Root_mean_square
Multiplier is sqrt( sqrt( (A^2+B^2+C^2) / 3) / 10) or ((A^2+B^2+C^2)/300)^(1/4)
Let's look at example:
Bloated Belote
10,10,10 => 1600 lp
10,28,28 => 2457 lp
Multiplier = sqrt( sqrt( (10^2+28^2+28^2) / 3) / 10) = sqrt( sqrt( 1668 / 3) / 10) = sqrt( 23,58 / 10) = 1,5356
1600 * 1,5356 = 2456,9
My 4 exhibits:
10/10/13 -> 474 LP Total: 33 Avg.q: 11
15/16/21 -> 596 LP Total: 52 Avg.q: 17.3
15/14/24 -> 608 LP Total: 53 Avg.q: 17.6
17/16/21 -> 606 LP Total: 54 Avg.q: 18
sqrt( sqrt( (17^2+16^2+21^2) / 3) / 10) = sqrt( sqrt( 986 / 3) / 10) = sqrt( 18,13 / 10) = 1,346
450*1,346 = 605,9