Percentage is an important topic of quantitative aptitude, Percentage is represented by % symbol and it means values per hundred.
Let’s consider following example
40% means 40 out of 100 and mathematically represented as 40/100.
To calculated percentage value let’s consider following example.
We have 20 black pebbles and 10 white pebbles; calculate how many percent black pebbles?
$\frac{100\times 20}{30}=\frac{200}{30}=50\frac{4}{3}=66.\mathrm{66\%}$
Formula is
$\frac{100\times \mathrm{Quantity}}{\mathrm{Total}}=\mathrm{\%\; Quantity}$