Why doesn't the Gemoro answer in the 3* cases, that the Pasuk rounds it off to the nearest 10?
Perhaps we can answer the Kushya on the Rosh, that there is a difference between Halacha & Agada.
In Halacha The Torah tells you to count 50 days or give 40 Malkos. Torah shel bal peh tells us the number
50 & 40 are inaccurate and should be 49 & 39 there we must claim that Torah rounded off to the nearest 10.
even though it's a Dochek answer.
In Agadah, Chazal have more leeway to Darshan the inaccurate number and explain it as correct according
to Drush and not to use the explanation of rounding off to the nearest 10 which is a Dochek.אמבצי
*1) Meraglim 2) Manna 3) Dovid Hamelech