Last time I looked, these questions were answered in the tutorials.

With decimal use % and /.

For instance, to get the hundreds digit [num]->[/ 100]->[% 10]

To extract bits, use the [&] object to mask out the bit you’re interested in, then optionally bit shift with [>>].

For instance, to get bit 3 (counting from *right* starting with zero) [num]->[& 8]->[>> 3].

If you just want to use the calculation to control a logic object (like if or a ggate), you can skip the bit shift.

These are really not Max-specific questions, they are fundamental DP techniques.