Stanford University Interview Test: 9^4^a = 4^9^a; a =? log(9^4^a) = log(4^9^a), (4^a)log9 = (9^a)log4, (9^a)/(4^a) = (9/4)^a = log₄9 a = [log(log₄9)]/log(9/4) = 0.2/0.352 = 0.568 Answer check: 9^4^a = 9^4^0.568 = 125.068, 4^9^a = 4^9^0.568 = 125.097; Confirmed The calculation was achieved on a smartphone with a standard calculator app Final answer: a = [log(log₄9)]/log(9/4) = 0.568