It will be an underestimate the answer is 43 I hoped that helped?
You would square 3968 and subtract 1.
The differences is 7 because I counted.
The value of the underlined digit depends on the place the number that is underlined is. For the first digit, it would be ones. The second digit is 10s. The third is 100s and the fourth is thousands and the fifth is ten thousands and the 6 is hundred thousands, and the seventh is million, and so on.