Ratio (source code)
= Ratio
{title2=$a:b$}
{wiki}
A ratio compares two quantities $a,b$, written $a:b$ and corresponding to <division> $a/b$ when $b\ne0$. Equal <ratios> of corresponding <lengths> characterize the scaling of <similar triangles>.
For example, $6:4$ and $3:2$ specify the same <ratio> because $6/4=3/2$. Multiplying both entries by the same nonzero scale preserves the <quotient>: $(ca)/(cb)=a/b$. This is useful when comparing mixtures or scaling a recipe; doubling both ingredient amounts preserves their <ratio>, while adding the same amount to both generally does not. For quantities with the same physical units, their <ratio> is <dimensionless>, connecting this elementary calculation with <dimensional analysis>.
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