46, 50, 23, 39, -78, -50 Find the wrong number in the following number series.

The correct answer is -78.

To find the wrong number in the given series, let us analyze the pattern of differences between consecutive terms.

The given number series is:
46, 50, 23, 39, -78, -50

Let us examine the transition from one term to the next:
1. First term to second term:
$46+2^2=46+4=50$
2. Second term to third term:
$50-3^3=50-27=23$
3. Third term to fourth term:
$23+4^2=23+16=39$
4. Fourth term to fifth term:
Following the pattern of alternating addition of squares and subtraction of cubes of consecutive integers, the next step should be subtracting $5^3$ (which is 125):
$39-5^3=39-125=-86$
However, the given fifth term is -78.

Let us verify if the sixth term is correct when using the expected fifth term of -86:
The next operation in the sequence is adding $6^2$ (which is 36):
$-86+6^2=-86+36=-50$
This matches the sixth term of the series (-50) perfectly.

Therefore, the wrong number in the series is -78, and it should be replaced by -86.