The expression “per cent,” which is an abbreviation of the Latin words
“per centum,” means “for each hundred.”
The symbol % is often used to denote “per cent.” Thus, 7 per cent, or
7%, means 7 parts out of every 100 parts, _i.e._, 7/100 of the whole.
Since per cent means hundredths, we may write any fraction whose
denominator is 100 as so many per cent. In some cases the corresponding
common fractions are so simple that it is advisable to remember them.
For example:
25 1
25% = --- = -,
100 4
50 1
50% = --- = -,
100 2
75 3
75% = --- = -,
100 4
33-1/3 1
33-1/3% = ------ = -,
100 3
66-2/3 2
66-2/3% = ------ = -,
100 3
5 1
5% = --- = --,
100 20
2-1/2 1
2-1/2% = ----- = --,
100 40
12-1/2 1
12-1/2% = ------ = -,
100 8
and so on.
The _number_ per cent is called the _rate_ per cent.