characters corresponding values
When converting something in an alphanumerical mode to a bitstream you first have to

1. Place them in groups of 2 : (n₁, n₂).
2. Convert them as so : (n₁‘s value * 45 + n₂‘s value).
3. Convert them to a 11-bit binary number : …
4. And so on : …
   When converting alphanumeric characters to a number why that formula specifically, and why * 45 and not any other number.

I’ve tried looking a bit into RS ECC and BCH ECC to see if it were connected,
Read through most QR Code structure guides,
I was expecting for the characters to be converted to the ISO-8599-1 character set’s binary version