PHP remainder function code _ PHP

I want to know what is 21712341byte in K bit, M bit, G bit? This is equivalent to the problem of hexadecimal conversion. But the hexadecimal value to be converted is 1024. The code is as follows:
// Obtain the value in the base space.
Function getRemainder ($ num, $ bin, $ pos, & $ result = 0 ){
// Author lianq.net
// $ Num value, decimal
// $ Bin: the hexadecimal format to be converted
// $ Pos digits
$ Real_len = log ($ num, $ bin); // logarithm, evaluate the original value length
$ Floor_len = floor ($ real_len); // trim
$ Base = pow ($ bin, $ pos-1); // base
$ Pisor = pow ($ bin, $ pos); // divisor
If ($ num >=$ pisor ){
$ New_num = $ num % pow ($ bin, $ floor_len );
GetRemainder ($ new_num, $ bin, $ pos, $ result );
} Else {
$ Result = floor ($ num/$ base );
}
Return $ result;
}

// For example, when a value 16 is converted to a 9-digit value, what is the value at the first place?
$ A = getRemainder (16, 9, 1 );
Echo $ a; // output 7