With each thumb in the air, we have the equivalent of decimal 33! The non-dominant thumb (for me, left) is worth 32, and the thumb on the dominant hand is worth one. Put them both together, and you get - again: decimal 33. What is that in duotrigesimal? "11 dtg" or - as I have decided to call it: "eleden"! That's right! It sounds like "eleven" - and even LOOKS like "eleven" (11 decimal); but it ISN'T "eleven"! It's "eleden"!
So, backing up a value, I hold up only my left thumb and say, "tuhn" (10 dtg)... Then I hold up both thumbs and say: "eleden" (11 dtg)...
Bye for now! ;)