Jane started off a multiplication process with the number 4.
John followed up by multiplying it by 4 also. This led the result to be 16.
Jane, being her turn now, times the current answer by 4 as required. The answer now is 64.
After a number of alternating multiplication by Jane and John, the result became 4 ,194 ,304.
Guess who did the last x4 operation (without using the calculator or equivalent).
The answer is not as difficult as seems to be. Just a simple stare at the alternate answers will solve the mystery.