**Percent**
(noun), **percentage** (noun): the first component is from
Latin per "for." The Indo-European root is per- "forward,
through, in front of," and many other things. The second
component is from Latin centum "hundred," from the Indo-European
root dekm-tom-, a form of dekm- "ten," because a hundred is ten
tens.

The word percent
means literally "for (each) hundred." In older American books
the full Latin phrase per centum was normally used. Later the
abbreviation per cent. appeared, and eventually the period after
the last letter was dropped. Modern usage allows percent as one
word or per cent as two words. The symbol that commonly
represents percent, %, may have originated from the second part
of p c°, an early Italian abbreviation of per cento. By the 17th
century the symbol o/o was in common use in Europe to represent
a percent. In any case, the current symbol, with its two
"zeros," is a convenient reminder that a percent is a fraction
whose denominator, 100, also contains two zeros.

So one percent is
simply one hundredth, 1% = 1/100, n% = n/100. Oftener than other
fractions, percents are percents of something, of another
quantity. For example, 5% of 120 is 120×5/100 = 6. A penny is
1%, a nickel 5%, a dime 10% and a quarter 25% of a dollar.

To grow by 100%
means to become twice as big, because a 100% growth means adding
100% of what was already there another 100% to the total of
200%. Losing 100% means losing everything.

Assume, your
stock in a XYZ company lost 20% of its value. It might have
been, for example, worth $1000 and by losing 20% (which is
1000×20/100 = 200) has the current worth of $800. What does it
take to get you money back? In other words, now starting at
$800, how much (in percents) you should gain so that your stock
is back to its original value of $1000? Do you think that, since
your lost 20%, all it takes to get back to $1000 is to gain your
20% back? Well, it is not so.

Obviously,
to make your stock worth the original $1000, you should gain the
lost $200. But $200 is now a portion of your current holdings of
$800, and is such is not 20% of the latter. (20% of $800 equal
$800×20/100 = $160.) So what portion of $800 is the amount of
$200? It's 1/4, of course. In terms of percents, seek a fraction
equal to 1/4 with the denominator of 100: 1/4 = 25/100 = 25%.)
So, here is a lesson to learn: it is easier to lose money than
to gain some.

Percents
provide a relative view of quantitative information. For
example,
it is known that, in the year 2000 elections, Ralph Nader
received more votes (2,800,000) than did Lincoln (1,900,000) in
1860. However, in 1860 there were less than 5000000 eligible
voters while in 2000 their number exceeded 100000000. Turning to
percents, Nader received 2800000/100000000×100% = 2.8%, whereas
Lincoln received a whooping 1900000/5000000×100% = 38%.
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