- Peninei Halakha
If, at a time when it is permissible to count, one’s friend asks him, “What is today’s omer count?” one should not answer, “Today is day such-and-such of the omer,” unless he has already counted with a berakha. If he says this, he will fulfill his obligation to count and will no longer be permitted to recite a berakha over that day’s count. Instead, one should answer, “Yesterday was such-and-such of the omer” (sa 489:4).
If one tells his friend which day of the omer it is while maintaining the specific intent not to fulfill his obligation, he may count later on with a berakha. If the day’s count is made up of both days and weeks (i.e., after the sixth day) and one tells his friend the number of days without mentioning the weeks, he may count later on, be-di’avad, with a berakha. Since he did not count in the normal fashion, mentioning both the days and the weeks, he has made it clear that he did not intend to discharge his obligation to fulfill the mitzva with this response (mb 489:22).
Before reciting the berakha, one should remind himself mentally what day of the omer it is (see sa 489:6, sht ad loc. 37). If, for example, one in uncertain whether it is the ninth day or the tenth day, and there is no one available to ask, he should say both numbers, thus fulfilling his obligation either way. However, the poskim debate whether one should recite the berakha in such a case. Some say that one may recite a berakha only over a clear and definite count. Others maintain that one may recite a berakha over a questionable count, because it is certain that one of the numbers is correct (see Piskei Teshuvot 489:17). In practice, one should not recite the berakha in such a case, since there is an uncertainty regarding the matter.