Meanings of thirteens in English

He found a ten, several thirteens, a seven, a six, but no nines.

Counting the corpse there were twenty-six of us, two thirteens.

I didn't know the thirteens at all.

Gethenians often think in thirteens, twenty-sixes, fifty-twos, no doubt because of the 26-day lunar cycle that makes their unvarying month and approximates their sexual cycle.

I remember one in particular who demanded "thirteens," but who did not stand more than five feet and five inches in his invisible stockings.

"There're a lot of thirteens in here," I said to myself.

"Does she wear size thirteens?"