11 Times Tables - The Dead Easy Way

Yes 11 times tables are dead easy to start off with. Sure you're good at it and can do it up to say 12 numbers. But can you figure out 11 x 23 in just two seconds? How about 11 x 256 in just six seconds? Or how about 11 x 8762453901288321?
Well I just taught how to solve these in a quick fashion to an ordinary 10 year old kid, who was struggling in his year 4 maths, in just one day.
And guess what, I'm going to show you how.



Let's start at the basics. How do you do 11 times tables?

Starting off with an easy question. Surely you can do this easily in a flash, the answer is;

No need to think about it at all. But what are the processes you were taught in school to solve a problem like this? Chances are it was something like this;

You start off with the ones column, 1 times 2 is 2.

Then you proceed to the next row, write down a 0 in the ones column and then do the multiplication highlighted in green, to give you 2. Hence now you have a 20.
*Note: To those who don't know why you add a 0 to the ones column, think of it this way, what is 10 times 2?

Then it is just a simple matter of adding the two numbers together to give you 22.
Are you following so far? Good.
Let's ramp it up a bit.

How are we going to do this?

23 times 1 is 23.

23 times 10 is 230.

Add the products together to give 253.
That's porbably how you were taught to do it.

For those of you who looked at this and noticed something, you got an a-ha moment.
For those who didn't, take a look at the last step. What numbers are you adding up?
You are adding up what you were given with to start off, 23, with that times 10 (or just a 0 on the back), 230.
That means without even having to do the multiplication, you can jump straight onto the additon part, skipping the first two steps.

So let's skip the first two steps and just write down the number 256 and that times 10, 2560. Then we add them together.

That right there is your answer. Dead-easy? Not quite yet, there's still some more step skipping we can do.
Now that you understand this much, let's look at the above example again, but now with the much anticipated dead-easy method.

You are given this. Now what I want you to do is ignore the 11 and focus only on the 256.

The number is 256.

 Firstly, just write down the end number, which is a 6.

Then focus on the last number and the second last number. Add these two numbers to give 11 (write down the number in the ones' column, which is 1, and remember the tens' column, you will need to carry it to the next sum).

 Next focus on the next two numbers, second from the left and third from the left. Add these two to give 7, but don't forget to carry the 1 from the previous sum. The result is 8.

Then you are up to the last number which you just plonk down in the front of the answer (don't forget to carry the 1 if the previous sum was greater than 9). So the answer is 2816, the same as above (phew).

There you have it, the simple technique to figure out your 11 times tables. This technique applies to all 11 times tables, no matter how big your other number is.
I got that 10 year old kid to do 11 times a ten digit number and he did within a minute.

If you followed this far congratulations.
Now the challenge is for you to do 11 x 8762453901288321. Good luck and see if you can do it in your head.

If you have any questions or comments, feel free to do so down below or through an email to me.
I won't bite, I promise :)