In the two previous post in Mathematics, we have discussed how to add and subtract signed numbers. In this post, we are going to learn how to multiply signed numbers particularly integers. Signed means positive and negative.
Positive Integer x Positive Integer
Clearly, the product is positive. We had been multiplying positive integers since Grade school and we all know that the product is positive.
Positive Integer x Negative Integer
When you multiply, notice that you are actually adding repeated. When we say 2 x 3, we are actually saying twice three or 2 groups of 3 or 3 + 3. When we say, thrice 11, we are saying 11 + 11 + 11. With this in mind, 3 x – 5 = -5 + -5 + -5. Since we are adding integers which are negative, the sum is also negative or -15. This means that 3 x -5 = -15. If we generalize this, we can say that the product of a positive integer and a negative integer is negative. » Read more