Solve Decimal Addition: 0.9 + 0.8 Using Number Blocks

To solve this problem, we'll follow these steps:

• Step 1: Align the numbers by their decimal points.
• Step 2: Add the numbers starting from the furthest right decimal place.
• Step 3: Handle any carryover if necessary.

Let's apply these steps to our problem:

Step 1: We align $0.9$ and $0.8$ so that their decimal points are in a column:
$\begin{array}{c} 0.9 \\ +0.8 \\ \hline \end{array}$

Step 2: Add the numbers starting from the rightmost digit (tenths place):
- In the tenths place, $9 + 8 = 17$. This results in $7$ in the tenths place and carry $1$ to the units place.

Step 3: Handle the carryover:
- In the units place, we consider any carry. Adding the carry $1$ from the tenths place gives us $1 + (0 + 0) = 1$.

So, the final result after addition is:
$\begin{array}{c} 1.7 \\ \end{array}$

Therefore, the sum of $0.9$ and $0.8$ is $\boxed{1.7}$.