As the sibling comment says, in my experience, the difficulty of formalizing the problem varies greatly between different areas. Probability theory is another notorious field in which modelling a problem correctly can be very subtle and difficult.

On the other hand, many problems in number theory and discrete structures tend to be rather simple to formalize. If you want to take your own look at that, I'd recommend to check out the lean games[1]. I'd say after the natural numbers game, you most likely know enough lean to write that problem down in lean with the "sufficiently small" being the trickiest part.

1: https://adam.math.hhu.de/