Equal Spacing of entities.

I'm trying to create a part that has six sets of holes on it. I want the holes equally spaced. Is there anyway to add this. I've tried linking the dimensions but it isn't letting me add the sixth dimension. I'm assuming it needs that last dimension to be different so that the other dimensions can fit into it.

Is there a formula or function that can allow for this?

I've included a screenshot of the situation.

Cheers,

SolidworksSketching