Solve the following problems and report answers with appropriate number of significant digits. $($Hint: Units MUST be the same for addition and subtraction but can be different for multiplication and division$)$

$1\mathrm{.}31cm2\mathrm{.}3cm=$

$5\mathrm{.}7621m6\mathrm{.}201m=$

$20\mathrm{.}2c\frac{m}{7\mathrm{.}41}s=$

$40\mathrm{.}002\frac{g}{13\mathrm{.}000005}g=$