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1/35: the model is 1/35 the size of the real thing.
If an object is 35 feet long, the model would be 1 foot long. It would take 35 models lined up end-to-end to equal the length of one of the real objects.
That's the basic idea of scale.
As far as "largest" and "smallest" scales go...I suppose theoretically there are no limits. I'm not really sure I understand what you're asking with that question.
For the same object, the size of the model would decrease as the number increases, and vice versa.
That is, a 1/16 scale Tiger is a larger model than a 1/35 scale Tiger, which is larger than a 1/48 scale Tiger, which is larger than a 1/72 scale Tiger, etc, etc.
How big a model is depends on how large the real object is coupled with the scale of the model.
So, a 1/35 Tiger II model would be larger than a 1/35 Sherman model , because a real Tiger II is a larger tank than a real Sherman.
Hope this helps!