La Fonction

Calculators

The calculator at the top multiplies any two numbers and updates as you type. Below it is every calculator page on the site, grouped by what people are actually trying to work out.

12 × 12 = 144

Adding 12 to itself 12 times gives the same answer.

Every page in this section

What the box above does

Two numbers in, the product out. It opens on 12 x 12 = 144 and accepts decimals, so 2.5 x 4 = 10 works as well. It multiplies and nothing else, which is more useful than it sounds: almost every check on this site is a multiplication run backwards. To test whether a fraction matches a decimal, multiply the decimal by the bottom number. To test a percentage, multiply the amount by the rate written as a decimal.

Fractions and decimals

A percentage is a multiplication

Write the rate as a decimal and the whole family collapses into one move. Twenty per cent off means multiplying by 0.8, so 45 x 0.8 = 36 is the price to pay. A rise of three per cent means multiplying by 1.03. Discounts, pay rises, interest and marks all end at the same box, which is why the pages below repeat one idea in different clothes.

Percentages, money and marks

Ratios

The last four are clinical numbers. The pages show the arithmetic and the usual reference ranges, and nothing on this site interprets a result for a particular person.

Also here

Multiplication grids and single tables sit on the charts side. The French pages, written in French rather than translated, are listed on calculatrices et tables.