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A cunning trick for multiplying 11 by double digits

Creative Resources for primary children| How do we learn| Education

June 17, 2024•1 min read

This is potentially one of my favourite times-tables tricks. I hope you find it helpful too

A few weeks ago, I was working with a lad, he’s brilliant, he’s just finished his GCSEs. We had just a couple of minutes left of the lesson, so we decided on a game of times-tables-noughts-and-crosses.

I pulled up the grid and asked what he’d like to multiply by. He answered 11.

Considering he was doing the higher paper I agreed but thought I’d ‘be clever’ and make the numbers in the grid double digits to make it harder.

But he was still answering them within a flash.

I asked if he was using a calculator and his mum, whom I hadn’t realised was also there, said he was just using a trick that he had learned.

This was eye-opening to me, so I thought I’d share it with you too:

Multiplying single digits by 11 is simple.

The digit you are multiplying by 11 is written down twice instead of once:

11x3 = 33

11x8 =88

And this apparently is how you multiply 11 by a double digit easily:

Simply add the 2 numbers you are multiplying by 11 together:

12x11

(1+2 = 3) and slide the answer (3) between the number you were multiplying 11 by: 132

16x11

1+6 =7

Split the 16 and put 7 in the middle

16x11 =176

Another example:

32x11

3+2=5

Split the 32 and place the 5 in the middle:

352

Why not give it a go and see how you get on.

Good luck!

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Dawn Strachan

For the past 20+ years I have been a firm believer that learning should be an enjoyable experience. I appreciate that traditionally education has revolved around worksheets, textbooks, listening to teachers. But a grounding in early years and working with children who had a variety of learning styles from I learned that it is an individual activity that is personal to all of us. We don’t all learn in the same way. Our influences, our experiences, our capabilities all influence how we retain information. But through it all, I believe that if we can make it enjoyable and engaging, they will want to participate. With participation comes practice which in turn boosts skill and confidence. With an increase in skill and confidence comes a willingness to have a go. This in turn leads to more practice which leads to a positive spiral of success. The moral, we need to make learning fun, engaging, use a range of techniques.

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