I know how to convert the fractional part of a number to a different radix, but I wonder if there is a way to do it more efficiently when only a limited amount of significant digits after the radix point is required in the result.
Suppose you have a number in base, say, 3, with a lot of digits after the radix point.
I would like to convert that number to base 10, but I'm only interested in the first two digits after the decimal point, so I'm going to use only a few digits in the base 3 operand and ignore the rest. But how many digits do I need to consider exactly in a general case? Is there a special algorithm for a base conversion with limited precision?