$\begin{array}{lcr}25‰& =& \frac{25}{1000}\\ & & \\ & =& \frac{\mathrm{2,5}}{100}\\ & & \\ & =& \mathrm{2,5}\%\\ & & \\ & =& \mathrm{0,025}\end{array}$

$\begin{array}{lcr}7‰& =& \frac{7}{1000}\\ & & \\ & =& \frac{\mathrm{0,7}}{100}\\ & & \\ & =& \mathrm{0,7}\%\\ & & \\ & =& \mathrm{0,007}\end{array}$

$\begin{array}{lcr}123‰& =& \frac{123}{1000}\\ & & \\ & =& \frac{\mathrm{12,3}}{100}\\ & & \\ & =& \mathrm{12,3}\%\\ & & \\ & =& \mathrm{0,123}\end{array}$

$\begin{array}{lcr}12‰& =& \frac{12}{1000}\\ & & \\ & =& \frac{\mathrm{1,2}}{100}\\ & & \\ & =& \mathrm{1,2}\%\\ & & \\ & =& \mathrm{0,012}\end{array}$

$\begin{array}{lcr}1000‰& =& \frac{1000}{1000}\\ & & \\ & =& \frac{100}{100}\\ & & \\ & =& 100\%\\ & & \\ & =& 1\end{array}$