First convert the given decimals into like decimals.
we get,
$$26.900, 19.740, 231.769 $$ and $$ 0.048 $$
Write the addends on under the other in column form, keeping the decimal points of all the addends in the same column and the digits of the same place in the same column,
Writing these decimals in column from and adding, we get,
$$ 26.900 $$
$$ 19.740 $$
$$ 234.769 $$
$$ 0.048 $$
__________
$$ 278.457 $$
Hence, the sum of the given decimals is $$ 278.457 $$