I was surprised to see the logarithm notation. Since I had never talked to him about logarithm before, and since he wrote it incorrectly, I assumed that he was playing, which was not like Mortaza. I told him this was logarithm and whether he knew what it meant. His answer: "It is the opposite of power." He then gave me an example. Then I asked him where he learned about it. He said from the calculator. And then in response to my question of "how," he showed me on the scientific calculator of his iPad, when he raised a number to the power of another number repeatedly, and then took the logarithm of the result in a similar base repeatedly, we got back to the original number.