Fill in the blanks so that the equality holds
`278xx(455xx629)=(278xx_______ )xx629`

Answer

To solve the equation \( 278 \times (455 \times 629) = (278 \times \_\_\_\_\_) \times 629 \), we will use the associative property of multiplication.

### Step-by-Step Solution:

1. **Understand the Associative Property**:
The associative property states that when multiplying three numbers, the way in which they are grouped does not change the product. For example, \( A \times (B \times C) = (A \times B) \times C \).

2. **Identify the Components**:
In our case, we have:
- \( A = 278 \)
- \( B = 455 \)
- \( C = 629 \)

3. **Apply the Associative Property**:
According to the associative property:
\[ 278 \times (455 \times 629) = (278 \times 455) \times 629 \]
This means that we can rearrange the multiplication without changing the result.

4. **Fill in the Blank**:
To make the equation hold true, we need to fill in the blank with the value of \( B \), which is \( 455 \). Therefore, we write:
\[ 278 \times (455 \times 629) = (278 \times 455) \times 629 \]
Hence, the blank should be filled with \( 455 \).

5. **Final Answer**:
The completed equation is:
\[ 278 \times (455 \times 629) = (278 \times 455) \times 629 \]

### Conclusion:
The blank can be filled with \( 455 \).