$1\mathrm{.}8$ Convert the decimal number $431$ to binary in two ways: $($a$)$ convert directly to binary;

$($b$)$ convert first to hexadecimal and then from hexadecimal to binary. Which method is faster?

$1\mathrm{.}9$ Express the following numbers in decimal:

$($a$)*(10110\mathrm{.}0101{)}_2$

$($b$)*(16\mathrm{.}5)$