Adding and Multiplying Even/Odd Numbers - Lesson 47

This is the video for lesson 47 on my web site, Adding and Multiplying Even and Odd Numbers.

There are certain properties that always hold true when we do calculations with even and odd numbers. This lesson just reviews them. Let’s take a look at what happens when we add an even number plus an even number.

The rule is that we always get in even number as answer. Now, these rules can sometimes be hard to memorize. What I usually do is just pick a simple even number and a simple odd number and I just see what happens. So to add an even and an even, I’ll just see what happens when I add two plus two because two just a small simple even number and we get four which is even. And it turns out that if you add any even number plus any even number, you get an even always. Let’s see what happens we add in an even and an odd.

I’ll add two as my even. And as simple as odd number is one. So, two plus one gives us three which is odd so adding an even plus and odd always gives us an odd. To add an odd plus an odd, the easiest thing to do is just add one plus one which is two and that actually gives us an even number as an answer. So whenever we add an odd plus odd, we always get even.

Now, it's important to understand that these rules here for addition also apply to substraction. Make sure that you see that. Do some experimenting to make sure you understand that. Now the rules for multiplication are little bit different so let’s go through them.

Let see what happens when we multiply an even times an even. I’ll do two times two and we get four which is even. Anytime we multiply even times even, we get even. For even times odd, I’ll just to do two times one which is an even and the rule is that whenever we multiply an even times an odd, we get an even as our answer. For odd times odd, I’ll just do one times one and get one which is odd and the rule is whenever we do odd times odd, we always get odd.

These rules that we have for multiplication also apply to division. Make sure that you see that. This is just a very basic simple lesson. But very often, you will get a test question that tests these facts. Rather than memorize these rules that can be tricky, I suggest recreating them whenever you need to. Just use two as a the simple even number and one as a simple odd number and see what happens and you’ll be able to re-create this rules if you’re asked about them. We’ll talk more about this later.


Transcription by: Scribe4you Transcription Services