### 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 $$-$$