Cool Math Trick To Multiply Two Digit Numbers

I think its important to show patterns in number and showing your students how easy Math is when you know how to use these patterns!

At the beginning of my Math course that I teach (grade 10 Academic Math)  I asked the students in my class to give me any two two digit numbers to multiply. Of course they picked big numbers, the two numbers they pick where 63 and 42.  I quickly gave them the answer of 2646 without using a calculator.  My students were in awe.  Of course they told me to do it again so this time they picked 56 and 91, I quickly gave the answer 5096.  They thought it was a trick and asked how I did it.  I said it was not trick its just simple math.  This when on a few more times I even bet them a few times when they used a calculator.

I asked them if they wanted to learn how I was calculating the question so fast and they begged me to teach them.  I showed them the following:

When multiplying two digit numbers all you need to do is follow the patterns!

Example: Multiply 41 x  24

Step 1:  We multiply the the first two numbers 4 x 2 = 8  and put that number first

                                                                        8

Step 2: Then we multiply the last two numbers 1 x 4 = 4 and we leave a space and put that number
             next.

                                                                         8__4

Step 3: Next we multiply the out side and inside numbers and add them together, 4 x 4 = 16 and
            1 x 2 = 2  then   16 + 2 = 18.  Since there is only space for one digit between the 8 and 4
            we put the 8 in that spot and carry the one over to the 8 making it a 9.

                                                                          984

The students love it and wanted me to test them with their new found knowledge. I think teaching math is about showing students how cool math and patterns in math can be.  The next day in class one of my students said she challenged he dad to a multiplying contest for money multiplying two digit numbers and who could do them faster by hand.  She won 20 dollars. lol

I have found a video on YouTube to help further explain this:
(his accent is great!)

https://youtu.be/_eZ-8-UzmZo


Enjoy!