Set A contains 0, 4, 5, 9, 11, 12, 13, 14, 19, ..., 20, 24, 25, ...

language/english/spelling/number.sets New

New entry, edited from material collected for the archive and not yet in a released version.

Problem

Set A contains 0, 4, 5, 9, 11, 12, 13, 14, 19, ..., 20, 24, 25, ...
Set B contains 1, 2, 3, 6, 7, 8, 10, 15, 16, 17, 18, ..., 21, 22, 23,
...  What is the rule?

[ Editor: posted by "Judy & Irv" in May 1998; only the reply quoting
it was collected. ]

Show solution

Numbers spelled with an even # of letters in one group.

-- John-O <John-Oster@ouhsc.edu>

[ Editor: for example ZERO, FOUR, FIVE, NINE (4 letters) and ELEVEN,
TWELVE (6) are in A; ONE, TWO, SIX, TEN (3) and THREE, SEVEN, EIGHT
(5) are in B. ]