Find the sum of 0.99995+0.88885+0.77775+0.66665+0.55555.

We need to find the sum of the given decimal numbers:
S=0.99995+0.88885+0.77775+0.66665+0.55555
Let's line them up vertically for addition:
\begin{array}{r@{\quad}l} 0.99995 \ 0.88885 \ 0.77775 \ 0.66665 \ 0.55555 \ \hline 3.88875 \hline \end{array}

Alternative method:
Each number can be rewritten as:

0.99995=1−0.00005
0.88885=0.88888−0.00003=
9
8
​
−0.00003
Let's just add the column values directly:

Sum of last digits (5th decimal place): 5+5+5+5+5=25 (Write 5, carry 2)

Sum of 4th decimal place: 9+8+7+6+5+2=37 (Write 7, carry 3)

Sum of 3rd decimal place: 9+8+7+6+5+3=38 (Write 8, carry 3)

Sum of 2nd decimal place: 9+8+7+6+5+3=38 (Write 8, carry 3)

Sum of 1st decimal place: 9+8+7+6+5+3=38 (Write 8, carry 3)

Sum of units place: $0+0+0+0+0+3=3$ $

Thus, the total sum is 3.88875.