I've just created simple online calculator with arbitrary precision, so users can have many digital places. Here it is:
Currently it's very simple, only can only divide (x/y) and multiply (x*y) but it's useful to play with divisions. My initial goal was play with divisions that have interesting results in the decimal places expansion, like "1/9998"
1/99998 = 0.00001000020000400008
But with a large arbitrary precision decimal places, the result is much more impressive (80 decimal places in this case):
1/99998 = 0.00001000020000400008000160003200064001280025600512010240204804096081921638432769
One future idea for this js library would be to have a parser that could understand expressions like: 10.5 * (1/3+1/(2**16))
May be convert this to the bignumber API syntax and then eval the result.
Try also some interesting divisions, that will display incredible results in the decimal places expansion:
1/99998 (will display powers of 2);
1/99997 (will display powers of 3);
1/998001 (will display sequential numbers);
1001000/997002999 (will display all powers)