Multiplying by 11

Quick…what’s 63 x 11?

It’s 693.  It’s really easy to multiply any two digit number with 11.  It’s a great trick to play with a 4th or 5th class as a mental warm up to a maths class.  If you’re old fashioned and still do the 11 and 12 times tables with your class, this can be a great extension too.  Everyone finds it easy to multiply single digits with 11, (repeat the number – 4 x 11 = 44), but it’s not the same easiness when you get to 11 x 11 and 11 x 12…or is it?

Here’s the trick so you can multiply 11 by any two digit number.  Let’s use 11 x 12 as our example.

  • First, take the number 12 and separate the two digits – 1 __ 2
  • Now add the digits together – 1 + 2 = 3
  • Place the answer in the middle of the two digits 132
  • So 11 x 12 = 132

It works for every two digit number: 43 x 11 = 473, 62 x 11 = 682, etc.  But what about when the two digits make more than 10, e.g. 46 x 11 isn’t 4106? You simply “carry your one” so… 46 x 11 = 506.

Last Update: August 9, 2017  

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