Me and my simple questions: Can I do this in FPGA?

You dont need to consider binary at all - it doesnt matter what base the number is in - the equation is still the same. All computers, maths programs and everything work in binary - decimal is just a convenient representation for the human brain to understand. Just imagine your inputs are decimal. It will only make a difference for the number of bits required for operation.

If the input range is 0-99, then you need 7 integer bits (0-127). You cannot get exact resolution to make .999999, you need to decide how many fraction 2^n bits you need. 6 fractional bits gives you precision to the nearest 0.015625. 12 bits = 0.00048828125.

But usually you can work backwards - what precision is required at the output? this can give you the precision at the input.