# What Is Percent?

The word *percent* is of Latin lineage:

**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°*,*per cento*. By the 17^{th} 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,

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

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

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

[A. K. Dewdney, pp. 9] tells an amazing anecdote

A man by the name of Smith was walking home from work when he spotted a $5 bill on the pavement. He looked around, picked it up, and put it in his pocket. His other pocket already contained a $10 bill. Smith smiled. "My wealth has increased by 50 percent," he said to himself.

Unfortunately, the pocket that held the $5 bill had a hole in it. When Smith got home, he discovered to his dismay that the $5 was missing. "That's not so bad," he said. "Earlier, my wealth increased by 50 percent, now it has decreased by only 33 percent. I'm still ahead by 17 percent!"

Here's an interesting problem [*Crimes and Mathdemeanors*, pp. 21-26]: a watermelon is 99% water. As one would expect, if a watermelon left under the sun, it loses some of its water contents (and, hence, some of its weight) to evaporation. Assume, that after a while water constitutes 98% of its remaining weight. How much of weight (in percents) has been lost?

Give it a thought before reading further.

**Note:** percent is the most fundamental part of the interest (on loan, mortgage) calculations.

### References

- A. K. Dewdney,
*200% of Nothing*, John Wiley & Sons, Inc., 1993 - L. Hathout,
*Crimes and Mathdemeanors*, A K Peters, 2007 - D. Niederman, D. Boyum,
*What the Numbers Say*, Broadway Books, 2003, p. 79 - S. Schwartzman,
*The Words of Mathematics*, MAA, 1994

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A surprise: it's not 1% (99% - 98%) but a tremendous 50%! How do you figure that? If originally the watermelon was 99% water, then the chewy part was just 1%. The same quantity became 2%

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