It seems like you've provided a sequence of numbers: \(1, -2, 3, -4\). If you have a specific question or task related to this sequence, please let me know! Here are a few common operations we could perform:

1. **Sum of the Numbers**:
\(1 + (-2) + 3 + (-4) = 1 - 2 + 3 - 4 = -2\)

2. **Product of the Numbers**:
\(1 \times (-2) \times 3 \times (-4) = 24\)

3. **Average of the Numbers**:
The average is the sum divided by the number of terms.
\(\text{Average} = \frac{-2}{4} = -0.5\)

4. **Absolute Values**:
The absolute values are \(|1|, |-2|, |3|, |-4|\), which are \(1, 2, 3, 4\) respectively.

Please specify what you would like to do with these numbers!