I got the week numbers using the T-Clock (suggested by Mikal Madsen).
Here is what I did:
Downloaded the T-Clock (binaries) (the file T-Clock.zip)
Extracted the Zip
- Ran Clock64.exe

- Miscellaneous -> Checked
"Use T-Clock's calendar" and "Show week numbers"

- Pressed Apply ->
OK (now the system clock changed)
- Left clicked the system
clock/calendar (Unchecked the "Always ask before opening this file", and pressed Run)



Now the calendar shows three months and the week numbers!
Note:
Note that at different parts of the world (USA, EU), the week numbers are defined differently. For example, in EU the first week of the year is the first week with at least 4 days. The default in T-Clock (2.4.0.) is the USA settings which means that Week 1 is the week containing January 1st. The behavior can be changed in the T-Clock settings, under Miscellaneous.