I covered the whole cake with fondant and then smoothed in normal way as you would with a round cake. I trimmed the fondant just over the holes of the number as I found it impossible to cover it all in one go.
Then I covered the area around the centers with strips of fondant. I covered up the seam with a fondant pearl border.
I tried for ages to get information on the internet and couldn't find any. I asked questions on here but did not get any replies.
There is bound to be a better way but like I said I have not found one.
Hope this helps, my center of the six turned out not brilliant and had to cover a few mistakes, but I was pleased at my first attempt.
having trouble attaching photo.
please see my pics numbers 60 birthday cake. 
Just found this, they show a number eight after the number 1.
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