Encyclopedia > Percent

  Article Content


A percentage is a way of expressing a proportion or a fraction as a whole number. A number such as "45%", "45 percent" is actually shorthand for the fraction "45/100". The word percent is also written per cent.

One may thus say, for example,

45 percent of human beings...
and this is equivalent to saying either of
45 out of every 100 people...
0.45 of the human population...

A percentage may be a number larger than 100; for example, 200% is doubling.

The symbol for percent "%" is a stylised form of the two zeros. (In computing, other names for the character include: ITU-T: percent sign; mod; grapes. INTERCAL: double-oh-seven.)

Table of contents

Confusion from the use of percentages Because percentages are always relative to the quantity they affect, several common mistakes arise when using then.


For example, an interest rate is given as a percentage like 10%. If this rises to 20%, it is incorrect to say "the interest rate has risen by 10%", because this actually means "risen by 10% of the original 10%", i.e. it is now 11%.

Instead, the expression "percentage points" is often used. So, in the previous example, one can say "the interest rate has increased by 10 percentage points".


Another common error when using percentages is to imagine that percentage increases and decreases cancel. A 50% increase from 100 is 100 + 50 = 150. A 50% reduction from 150 is 150 - 75 = 75. In general, the net effect is (1+x)(1-x)=1-x2, or a net decrease proportional to the square of the percentage change.

Owners of dot com stocks came to understand that even if a stock has sunk 99%, it can nevertheless still sink another 99%. Also, if a stock rises by a large percentage, you're still broke if the stock subsequently drops 100%.

See also


All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
Shoreham, New York

... 1.1 km² (0.4 mi²) of it is land and none of the area is covered with water. Demographics As of the census of 2000, there are 417 people, 145 households, and ...

This page was created in 23.7 ms