? = 0.8 + 0.88 + 0.888 + 0.8888 + 0.88888

Answer

To solve the question \( ? = 0.8 + 0.88 + 0.888 + 0.8888 + 0.88888 \), we will add these decimal numbers step by step.

### Step 1: Align the Numbers
First, we will align the numbers by their decimal points for easier addition:

```
0.80000
+ 0.88000
+ 0.88800
+ 0.88880
+ 0.88888
```

### Step 2: Add the Numbers Column by Column
Now, we will add the numbers starting from the rightmost column (the smallest decimal place) to the left.

1. **Rightmost Column (5th decimal place)**:
- \( 0 + 0 + 0 + 0 + 8 = 8 \)

2. **4th Decimal Place**:
- \( 0 + 0 + 0 + 8 + 8 = 16 \)
- Write down 6 and carry over 1.

3. **3rd Decimal Place**:
- \( 0 + 8 + 8 + 8 + 8 = 32 \)
- Add the carry over: \( 32 + 1 = 33 \)
- Write down 3 and carry over 3.

4. **2nd Decimal Place**:
- \( 8 + 8 + 8 + 8 + 0 = 32 \)
- Add the carry over: \( 32 + 3 = 35 \)
- Write down 5 and carry over 3.

5. **1st Decimal Place**:
- \( 0 + 0 + 0 + 0 + 0 = 0 \)
- Add the carry over: \( 0 + 3 = 3 \)

### Step 3: Combine the Results
Now, we combine the results from each column:

```
3.58868
```

### Final Result
Thus, \( ? = 3.58868 \).