To change the number of decimal places you see, do this:
scale=5
ibase and obase determine the "input base" and the "output base," so you can use them to do conversions. See them like this:
obase 10 ibase 10
Set them like this:
ibase=2 ibase 2 ibase=1010 ibase 10 obase=8 obase 10
Why does obase say 10, when it should be 8? Well, because you set the output base to 8, and 10 octal is 8 decimal. Crazy, huh? I suppose displaying the value of obase always yields 10.
So pretend you want to convert from octal to binary. Do this:
obase=2 ibase=8 357 11101111