chiuc-.

Headword: 
chiuc-.
Principal English Translation: 

combining form for numbers that have a sub-base of 5, e.g. chiucnahui = 9

Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 59

Attestations from sources in English: 

Interestingly, mācuīlli (5), is not used in combinations that stand for 6 through 9. Richard Andrews suggests that chico- (chiuc- etc.) relate to the meaning "to one side," a "special form of the adverbialized nounstem." and "The compound stem therefore means something like 'the count on one hand (indicated by the matrix stem) with the addition of the full count of five already made on the other hand.'"
James Richard Andrews, Introduction to Classical Nahuatl, vol. 1 (Norman: University of Oklahoma Press, 2003), 310.

chicuacē = 6
chicōme = 7
chicuēyi = 8
chiucnāhui = 9
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 59