Are you writing a game ?
The only reason I can guess to sort a list into a random order would be shuffling a pack of cards.
If the absolute value of the random number is unimportant, i.e. you just want to use the randomness to arbitrarily sort another list into a random sequence, then you don't need to do the multiplication, rounding down, or adding one.
The code will be a lot more efficient if you just use the default value of rnd() in the random column and sort by that alone.
The maths processor will just be filling a string of bits (probably 64, but I've no real idea of the architecture - the more, the randomer) with 1 or 0, based on some other, hopefully unpredicable variable.
In the very early days of DOS 1.0 (yes I really was around then), the Basic compiler was included and the random number function was anything but.
If you booted the machine, and ran a program that printed a random number, it would always be the same one.
They generated "random" numbers in a way that had the appearance of randomness, but always started by using some fixed point in the architecture. This made it extremely shaky if the function was being relied on for encryption, a bit like the sloppy operators who allowed us to break German Enigma codes in WW2, by always starting their messages with the same "Hello Otto, it's me again"
For the sake of example. If the register used to generate the random value were 8 digits, then the possible values would be the 256 numbers between
0000 0000 and 1111 1111
Having generated this string of bits, the value 1 0000 0000 would be assigned the arbitrary value of 1 (decimal) and the value would be presented to you as a decimal value between 0 and 255/256 (.996)
The larger the number of bits in the string, the finer the gradation of randomness, between 0 and .99999999999999999999999999999999999999999999999999999999 etc.
If you're just using the random number as a means of shuffling another list, there's no point in mutiplying rounding and adding.
If you're trying to randomly sort them into 6 groups, then you'll need to use the code as quoted.