Mathnasium 247 Shoreline Hwy, #A3, Mill Valley CA 94941 (415) 384-8272   millvalley@mathnasium.com

Contact Us for A Free Assessment

* indicates a required field
  • phone number format invalid
  • email format invalid
Problems detected, please review the form.
protected by reCAPTCHA
Privacy - Terms

News from Mathnasium of Mill Valley

Multiplying by 11

Feb 3, 2019

It’s very easy to multiply any number by 11 if you know this little trick.  For example let’s take the number 43. Add the numbers 4 and 3 and you’ll get 7. Then put the number 7 between the numbers 4 and 3. And you’ll get the result 473.   
 
Now let’s extend the challenge and do the same with the number 78. Add the numbers 7 and 8 and you’ll get 15. But then don’t put the number 15 between the numbers 7 and 8, instead put the second digit, number 5, between the numbers 7 and 8 and add the first digit, number 1, to the number 7. You’ll get the result 858 which is the correct result.