Exploding dice continuum problem

If I carry out an exploding die roll are there forbidden numbers

For example if I roll 1d6 exploding you can never get a multiple of 6 for the final result e.g. {6,12,18,...} 

One solution would be to set the lowest number of the die to zero, instead of one, but I don't think that is possible using the standard roll20 dice roller?

If you use the penetrating exploding dice modifier, any exploding dice have a -1 applied to them. it looks like this:

/roll 1d6!p

Thanks I will give it a go.

To scale it from zero I can do the following

 /roll 1d6!p-1

 However it won't work for multiple dice 3d6!p-1 instead I will have to put the roll formulae in long hand, like this.

/roll (1d6!p-1)+(1d6!p-1)+(1d6!p-1)

You can also do

/roll 3d6!p-3

It'll get the same total

But do you really need a -1 on the first roll? Most games that apply a -1 apply it only to the exploding dice. If you roll 1d6-1, you cant get a natural 6.