If you want week numbers in the calendar, you can use `ncal -w` and they'll be the last row. Add a `-3` and you get:
$ ncal -w3
July 2025 August 2025 September 2025
Mo 7 14 21 28 4 11 18 25 1 8 15 22 29
Tu 1 8 15 22 29 5 12 19 26 2 9 16 23 30
We 2 9 16 23 30 6 13 20 27 3 10 17 24
Th 3 10 17 24 31 7 14 21 28 4 11 18 25
Fr 4 11 18 25 1 8 15 22 29 5 12 19 26
Sa 5 12 19 26 2 9 16 23 30 6 13 20 27
Su 6 13 20 27 3 10 17 24 31 7 14 21 28
27 28 29 30 31 31 32 33 34 35 36 37 38 39 40