Let the concatenation abc represent the last three digits of the 7th power of randomly chosen 4-digit integer.

Evaluate the probability that at least one of the digits a,b, or c is zero.

Bonus (D4) task: Still addressing the last 3 digits, derive a formula for p(k,l) expressing the probability for the l-th power of k-digit number, l must be prime in respect to 10 , and no less than k.