First of all, a negative times a negative times a negative would end up as a negative, so we got that covered. Now all we need is the arithmetic part. 6 x 3 = 18, and 18 x 2 = 36
so if 2 number with the same sign are multiplied togher, the result will be positive so if (-) times (-)=(+) and (+) times (-)=(-) then (-) times (-) times (-)=(-)
so just multiply them so -6 times -2=+12 +12 times -3=-36