If the command should work with both tabs and spaces as the delimiter I would use awk:
awk '{print $100,$101,$102,$103,$104,$105}' myfile > outfile
As long as you just need to specify 5 fields it is imo ok to just type them, for longer ranges you can use a for loop:
awk '{for(i=100;i<=105;i++)print $i}' myfile > outfile
If you want to use cut, you need to use the -f option:
cut -f100-105 myfile > outfile
If the field delimiter is different from TAB you need to specify it using -d:
cut -d' ' -f100-105 myfile > outfile
Check the man page for more info on the cut command.