3(-4)(5)(-2) = 120  The answer is a positive number.  There are two ways of doing this:  3(-4) = -12 and -12(5) = -60  and a -60(-2) = 120   You can do this problem by multiply  two numbers together at a time and use the previous rules.   OR   In a multiplication problem count the number of negative signs in the total problem. If the total number is even the answer is positive and if the number is odd the answer will be negative.  For example  -4(3)(-6)(-1) = -72  There are 3 negative signs in the problem so the answer is negative. If the problem was  -4(-3)(-6)(-1) the answer would be a positive 72 because there are 4 negative signs in the problem.