wierd math thing?

[bobhustead]

I had to take symbolic logic instead of real math to satisfy my math requirement in undergrad, so if this post looks "slow", I apologize. I just "discovered" that if you pick any number (at least up to 4 digits) and square it and then multiply the number immediately below the squared number by the number immediately above it, the product is one digit less than the square. Can anyone explain what is behind this?
Bob

 

[BobHaskell]

number = x
number squared = x * x or x^2
number below = (x - 1)
number above = (x + 1)
product = (x - 1) * (x + 1), evaluate FOIL

x * x - (x -1) * (x + 1) = x^2 - ( x^2 + x - x - 1 ) = x^2 - ( x^2 - 1) = x^2 - x^2 + 1 = 1

 

[BobHaskell]

From childhood: pick a number between 1 and 10. Double it. Add 6. Divide by 2. Subtract the number you started with. Your answer is 3.

 

[DocDup1]

Yea, what they said.

 

[3798j]

 

[Boink]

Reminds me of a hilarious joke that was on Cheers many years ago... and I'm too lazy to find it on YouTube.
My version/recollection is:
Cliff Claven is talking to Norm in the bar (and it was an election year)... and he tells Norm (something like):
"Did you know that if you take the name of any president of the USA and convert all the letters to numbers... then add those numbers, take the square root, then multiply by 5 and finally convert the new number back to letters you can learn the name of the next president in the sequence?!"
Norm looks up from his beer surprised, and asks Cliff "so, who's going to be the next president of the USA?"
Cliff responds: "according to my calculation, it's going to be a guy named Yelnick McWawa."