Q. On the first night of sefirah before counting, a joker asked the fellow next to him what day of the sefirah is it tonight? He answered, also as a joke: I'm not sure but I think it is the first day of the omer, could he still count latter on that night with a bracha?
A. Horav Shlomo Miller Shlit"a pointed out that Poiskim make clear that Sefiras Haomer is an act of counting. As such, by definition, counting has to have a degree of certainty; consequently mentioning, "he is not sure" contravenes the essence of what counting is. See Teshuvas Harashbo (235) and Baal Hamo'or (end of Pesachim). Dvar Avrohom (1: 32) explains with this principle, why there is no "Sfeiko Deyomo" in regards to Sefiras Haomer.
There may be an additional consideration that it is obvious from the answer given, that his intention was not to count as a mitzvah but to answer jokingly. This could be analogous to counting expressly with the intention not to comply with the mitzvah mentioned in Mishna Berura (489: 17).
Horav Shlomo Miller Shlit"a opinion is that he can still count with a brocho.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit"a.
Important Numbers
