The Rosh explains that even though it
says fifty days it means forty nine days
but the Torah rounds it off to the nearest
ten the same way as when the Torah
tells us to give forty Malkos it is actually
thirty nine and rounded off to the nearest 10
We also find the Torah says they came
down to Mitzrayim with 70 people and
actually there were only 69.
( רא"ש סימן מ' ערבי פסחים)
n Ta'anis 29a The Pasuk says the
Meraglim returned after 40 days the Gemoro
asks it was only 39 days
In Kidushin 38a on the Pasuk that they atethe Manna for 40years the Gemoro asks, it
was 40 years minus 30 days.
In Sanhedrin 107b the Gemoro asks on the
Pasuk that Dovid Hamelech was king for
7years (Chevron) + 33 years (Yerushlayim)
and the other Pasuk it says He was king in
Chevron 71/2 years
According to the Rosh why doesn't the
in these 3 cases,
that thePasuk rounds it
off to the nearest 10?