Homework Help Forum: math

Posted by Mattie on Monday, September 28, 2009 at 4:53pm.

I am doing 4th grade number sense are there any cool math tricks or short cuts that would be good for me to know.

• math - angela, Monday, September 28, 2009 at 5:28pm

  what kind of questions are you doing?

  
  

• math - Reiny, Monday, September 28, 2009 at 5:33pm

  here is a neat one: multiply any number by 11 e.g. 45821 x 11 = 504031 starting from the right, add up all the digits in the odd positions 1+0+0 = 1 now add up the ones in the even positions 3+4+5 = 12 What is the difference between them ? I will always be a multiple of 11, that is, 11 22 33 etc The difference could also be zero, zero is considered a multiple of 11.

  
  

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