Quote: To square, subtract 1 to obtain 40 and add 1 to obtain 42. Next multiply 40 x 42. Don't panic! This is simply a 2-by-1 multiplication problem (specifically, 4 x 42) in disguise. Since 4 x 42 = 168, 40 x 42 = 1680. Almost done! All you have to add is the square of 1 (the number by which you went up and down from 41), giving you 1680 + 1 = 1681.
Question: Seriously, how are you supposed to just do this in your head?
Comments: Alright, I wasn't sure when this was due because you didn't have a due date. It took me a while to read. I found this quote most interesting because I know a lot of equations involve squaring numbers. I mean, in my head, I just knew there was a way. It was multiplication, there is usually some pattern in that. Even so, I highly doubt I could remember this process well enough. It's a little complicated and I would actually rather use a calculator. That is all.