Add:

35.67, 18.794, 4.9, 31.82

Maximum number of decimal places in given decimals is 3. So, we convert them into like decimals, each having 3 places of decimal, by annexing zeros.

Thus, we get: 35.670, 18.794, 4.900 and 31.820

On adding column-wise, we get:

$\begin{array}{r} 35.670 \ 18.794 \ 4.900 \ +\phantom{0}31.820 \ \hline 91.184 \ \hline \end{array}$

Hence, the sum is 91.184