296. Forgetting if One Bentched

44:10 When Shabbos is also Rosh Chodesh, a Festival or a Chol HaMoed, we say the paragraph R’tzei (for Shabbos) before Yaaleh v’Yavo (for the other occasion). This is because Shabbos occurs more frequently and the principle is that we say the more common thing before the less-common thing. (If one accidentally reversed the order, he has still fulfilled his obligation in bentching – Mishnah Brurah 188:13.) 44:11 If someone forgets whether or not he already bentched, if he has eaten until he is satisfied, he must bentch again. This is because bentching when satisfied is a Biblical obligation, for which we act stringently in a case of doubt. Similarly, if one nods off while bentching and, when he awakes, he doesn’t recall how far he got, he must go back to the beginning. A woman who does not recall whether or not she bentched need not repeat it because there is a doubt whether women are obligated Biblically or Rabbinically. (Nevertheless, if she wishes to bentch in such a case, she may – see Mishnah Brurah 186:3 and Bi’ur Halacha 186:1 s.v. elah m’d’rabbanan.)