But I can't type 999999999999999999999999999999n to Snap! blocks. If I could then all arithmetic blocks would automatically support big integers.
Yes, this would not address the support for rational numbers and more that the BigNum library currently supports. But this would work without loading any libraries.
Yeah this is kind of a deal-killer. But if you want to use it anyway, just write an ID block that reports its input to escape from the restrictions of the Number-type input slot.