secrets-of-mental-math-malestrom

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Foreword
math and make sure the numbers were right. Well, Secrets of
Mental Math can help you handle all kinds of numbers. You’ll
get comfortable with calculations in a way that will let you know
some of Nature’s numerical secrets, and who knows where that
might take you?
As you get to know numbers, the answer really is at your
fingertips. That’s not a joke, because that’s where it all begins.
Almost everyone has ten fingers, so our system of mathematics
started with 1 and went to 10. In fact, we call both our numbers
and our fingers “digits.” Coincidence? Hardly. Pretty
soon, though, our ancestors ran out of fingers. The same thing
has probably happened to you. But we can’t just ignore those
big numbers and (this is a joke) throw up our hands.
We need numbers—they’re part of our lives every day, and in
ways we typically don’t even notice. Think about a conversation
you had with a friend. To call, you needed a phone number, and
the time you spent on the phone was measured in numbers of
hours and minutes. Every date in history, including an important
one like your birthday, is reckoned with numbers. We even
use numbers to represent ideas that have nothing to do with
counting. What’s your 20? (I.e., Where are you? From the old
police “10” codes, like 10-4 for “yes.”) What’s the 411 on that
gal? (I.e., What’s her background; is she dating anyone? From
the number for telephone information.) People describe one
another in numbers representing height and weight. And, of
course, we all like to know how much money we have or how
much something costs in numbers: dollars, pesos, yuan, rupees,
krona, euros, or yen. Additionally (another joke), this book has
a time-saving section on remembering numbers—and large numbers
of numbers.
If, for some reason, you’re not crazy about math, read a little
further. Of course I, as the Science Guy, hope you do like math.