It's a bit more nuanced than that because, as I say, Perl isn't strongly typed. However it's still something I would encourage as good practice because:

1. It makes your intention in the code very clear
2. It will certainly make a difference when you start working in bases other than decimal
3. It doesn't hurt

While learning you can always try quick one-liners to see what happens when you try something. Feel free to experiment on your own. If you see behaviour you don't understand try to find it in the documentation or ask about it here.