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## #1 2011-09-22 23:32:45

John E. Franklin
Star Member

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### rough eighths of an inch trick

25.4 divided by 8 is within one-half
of a percent of the square-root of
ten.  This is interesting to note, in
case you are a carpenter or mechanic
with poor math skills and can't
remember if you should divide or
millimeters, you can go either direction
by just multiplying or dividing by
the square-root of 10 on any
simple calculator.  If the answer looks
too small in one case, you hit the
wrong button and now you are in
This is because the reciprocal of the
square-root of ten looks the same
except the decimal point is moved
over.  If you are going from millimeters
to inches and you press the wrong
multiply button instead of divide, then you
will end up close to 80ths of an inch, and
hopefully you will then either move over
the decimal place or do the problem
I know this is very silly, but I had to
share something with you today!!!!

igloo myrtilles fourmis

## #2 2012-04-15 11:30:30

anonimnystefy
Real Member

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### Re: rough eighths of an inch trick

That is really cool fact! What is the dimension of the inch actually defined?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

## #3 2012-04-15 14:26:54

bobbym

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### Re: rough eighths of an inch trick

Hi John E. Franklin;

No it isn't silly. As always I liked it.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.