In mathematics, a ratio is a relationship between two numbers of the same kind (e.g., objects, persons, students, spoonfuls, units of whatever identical dimension), usually expressed as "a to b" or a:b, sometimes expressed arithmetically as a dimensionless quotient of the two which explicitly indicates how many times the first number contains the second (not necessarily an integer). In layman's terms a ratio represents, simply, for every amount of one thing, how much there is of another thing. For example, supposing one has 10 pairs of socks for every pair of shoes, the ratio of shoes:socks would be 1:10 and the ratio of socks:shoes would be 10:1.
The ratio of numbers A and B can be expressed as:
The numbers A and B are sometimes called terms with A being the antecedent and B being the consequent.
The proportion expressing the equality of the ratios A:B and C:D is written A:B=C:D or A:B::C:D. this latter form, when spoken or written in the English language, is often expressed as
Again, A, B, C, D are called the terms of the proportion. A and D are called the extremes, and B and C are called the means. The equality of three or more proportions is called a continued proportion.