this is right! this is how binary to decimal conversion works. the BNs are the the powers of two: each digit is the previous increased by itself => each digit is the previous multiplied by 2 => nth digit is 2 to the nth power.
positional base for a given B works the same way if you change "add all the powers of two where there is a one" to "add all the powers of K multiplied by the corresponding digit" (these are equivalent if K is 2; multiplying something by 0 is 0)
say you want to get the decimal number of the octal number 5756. let's get the powers that we need:
- 83 = 512
- 82 = 64
- 81 = 8
- 80 = 1
and 5*512 + 7*64 + 5*8 + 6*1 = 3054. this will work for every octal(/binary) number!