Express the indicated degree of likelihood as a probability value?

Question

"You cannot determine the exact decimal-number value of n."

Answer 1

The probability of something that cannot be done (ie. it's impossible) is always 0 (zero). Hence,

P(You can determine the exact decimal-number value of n) = 0,

where P indicates the probability of the event detailed in the brackets. Alternatively, you can reformulate this as follows:

P(You can't determine the exact decimal-number value of n) = 1.

Answer 2

You haven't provided any degree of likelihood for us to express as a probability value.