How to multiply any two digit number by 11
Let me make an assumption, you've all done your times tables. And I'm guessing that some of you may have learnt this, but the majority of you have not. I am going to teach you how to multiply any 2 digit number by 11. So lets say that we take 36 as our two digit number. What is 36 * 11? To find out the answer, take these three steps:
1. Split the number into 2 seperate digits, so we have 3 and 6.
2. Add those together. So now we have 9.
3. Put your result in the middle of the original two numbers. So we get 396.
A quick check on a piece of paper or a calculator will show you that 36 * 11 does indeed equal 396.
But there is a problem. What if you tried 38 * 11?
Well, 3 + 8 = 11 so the answer should be 3118 right? No. In this case (when the sum of the two numbers equals 10 or more), you must carry over the 1 to the 3 to make it a 4. So your answer is no 418. A check will show that it is in fact 418.
There you go. You can now go and impress all of your friends with this simple little trick.
Yours in numbers,
Noah
1. Split the number into 2 seperate digits, so we have 3 and 6.
2. Add those together. So now we have 9.
3. Put your result in the middle of the original two numbers. So we get 396.
A quick check on a piece of paper or a calculator will show you that 36 * 11 does indeed equal 396.
But there is a problem. What if you tried 38 * 11?
Well, 3 + 8 = 11 so the answer should be 3118 right? No. In this case (when the sum of the two numbers equals 10 or more), you must carry over the 1 to the 3 to make it a 4. So your answer is no 418. A check will show that it is in fact 418.
There you go. You can now go and impress all of your friends with this simple little trick.
Yours in numbers,
Noah
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