Theory:

Multiplication:
When more than \(2\) numbers are multiplied, depending upon the number of negative numbers involved, the sign of the answer varies.
We know that,
 
\((-1) × (1) = -1\)
 
\((-1) × (-1) = +1\)
 
Now,
 
\((-1) × (-2) × (-3) = -6\)
 
\((-1) × (-2) × (-3) × (-4) = +24\)
 
\((-1) × (-2) × (-3) × (-4) × (-5) = -120\)
  
Inference:
  
When \(2\) negative numbers are multiplied, the result will be a positive number.
When \(3\) negative numbers are multiplied, the result will be a negative number.
When \(4\) negative numbers are multiplied, the result will be a positive number.
 
Conclusion:
  
From the above, we can conclude that,
 
Number of negative integers in multiplication
Sign of the result 
Even
\(+\)
Odd
\(-\)