History of percentages

[simont]

My 10 year old daughter asked my wife this evening "Why do we use percentages, why don't people just use fractions?"  Before I provide the answer we told her I thought I would open this out for discussion.  Any advances on "... because fractions and decimals make people twitchy!"?

[tomd]

You can't round fractions..? They also take more thinking about to judge, and operations are made much harder.

[magicdice]

well, what's bigger, 2/7 or 13/50?

how about 29% or 26%?

with fractions, it takes a moment to see. whereas with percentages, they are easier to compare. 100 is a nice round number, and although 29/100 isn't precisely 2/7, it's near enough for most day-to-day purposes. plus, 34% looks neater than a fraction, particularly in the days of word-processing where there is no clear way to get most fractions.

plus, working with percentages saves all finding-a-common-denominator business which is quite time-consuming.

[fo3nix]

percentages are fractions. Just ones that always have 100 in the denominator.

[Gef]

Percentages have 100 in the numerator not the denominator.

[magicdice]

Gef you're wrong. the numerator's the top bit.