One flourist (russian one) told me that even number of flowers are for funerals, because the word "чётный" - even number - has the same root as "сочтены" (дни)

One flourist (russian one) told me that even number of flowers are for funerals, because the word "чётный" - even number - has the same root as "сочтены" (дни) - days are counted. Probably it's similar in other Slavic languages.