Slightly off topic but I'm impressed you found this thread buried so far down. I was just complaining about how this style of consolidated long term discussion doesn't work in Lemmy and other Redditlikes, which is why I abandoned this post in favor of just making new posts.

Now, on to your question. Commonthroat uses a base 12 number system because the majority of its speakers are surface-dwellers who primarily use their forefeet to manipulate objects. Outlander uses a base 24 system because there are far more speakers who are spacers living in zero-G who can use all four paws.

Quoting from the Outlander scratchpad thread on the CBB forum:

After reading the Wikipedia article on Classical Nahuatl, I was captivated by the fact that cardinal numbers are transparently derived from other words. I think this will be the case with Outlander. Further, since both Moonlitter and Partisan Territory have a large population of spacers, Outlander will have a base-24 number system for larger numbers, with numbers 1-24 clearly deriving from anatomical terms for digits and paws.

Here's what I have from the auto-generated Swadesh list:

one: snl two: qdc three: rMn four: sMP five: rC

When Outlanders count, they start with the left forepaw curled into a fist, with the inner thumb in front of the other digits and the outer thumb behind. For each number from one to six, a digit is uncurled, starting with the writing claw, then each digit from medial to lateral. The inner thumb is opened next representing five, and the outer thumb last for number six. This process continues with the right forepaw for numbers seven to twelve.

For surface dwellers, that's all the fingers they can practically use while reared up on the hind feet, but since the Outlands contains a large population of spacers, who use all 24 digits to count, the number system for the language as a whole reflects the spacer usage. When counting on the rear paws, the ankles are rotated 180 degrees such that the palm of the paw is facing outward (such a range of motion is common in arboreal animals).

The word for six is , derived from paw. For numbers seven-twelve, the numbers for one to six are suffixed with a chuff, from a reduced form of (right)

six: rkg seven: snlr eight: qdcr nine: rMnr ten: sMPr eleven: rCr twelve: rkgr

For numbers 13 to 23, the corresponding lower numbers are prefixed with <geg(s)->. The etymology is obscure, but it likely relates to the word for the palmar pads, reflecting the state of the paws when counting higher numbers, with all four palms facing outward showing the pads. The prefix is a yip stem. The final yip is elided in front of another yip, and a huff or chuff of the following syllable is geminated.

The expected word * for twenty four is sometimes seen when people are imitating puppyish speech patterns, similar to words like ninty-eleven for 101. The usual term is , which is a transparent derivative of (palm). , when used in the numeral sense, can itself be pluralized to yield <qGqql< "twenty-fours" to mean multiple sets of 24.

thirteen: gegsnl fourteen: gegqqdc fifteen: gegrrMn sixteen: gegsMP seventeen: gegrrC eighteen: gegrrkg nineteen: gegsnlr twenty: gegqqdcr twenty one: gegrrMnr twenty two: gegsMPr twenty three: gegrrCr twenty four: *gegrrkgr, qGq

For even higher numbers, the word (with/and) is used to join a lower numbers to . 25 is , "24 with one" 26 is "24 with two" and so on. is frequently dropped to yield and so on.