Reference for Bekhorot 40:7

מאי איכא בין ר' עקיבא לר' יהושע

we say that a part of the day is considered equivalent to the whole day.<span class="x" onmousemove="('comment',' That a part of the last day of the discharge is considered as a whole day, and therefore we can say that it became pregnant on that very day, so that the animal was born on the last day of its first year, even after allowing for five full months for the pregnancy.');">⁴</span>

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