Variantly: One verse states "Six," and another "Seven." How are these two verses to be reconciled? Six from the new crop; seven from the old. (i.e., If he wishes to eat matzoth from the new crop, he can do so only for six days, it being forbidden on the first day, until after the offering of the omer [viz. Leviticus 23:15]).
The Reason Is That on the First Day of Passover
Mekhilta Tractate Pischa 8:6