Multiplying by 9 cool ways

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Taught by YourMathGal
  • Currently 4.0/5 Stars.
8123 views | 6 ratings
Meets NCTM Standards:
Lesson Description:

This video shows you easy ways to multiply single digits by 9, and larger numbers when all the digits are the same, like 88888 x 9...really easy and fun to do!

More free YouTube videos by Julie Harland are organized at http://yourmathgal.com

Questions answered by this video:
  • How do you multiply a single-digit number by 9 with your fingers?
  • What are some cool ways of multiplying by 9?
  • How do you multiply 9 times 3 with your fingers?
  • How do you multiply 9 times 6 with your fingers?
  • What are some patterns that occur when multiplying by 9?
  • How do you multiply large numbers by 9?
  • How do you multiply 9 times 33, 44, 77, or 88 without a calculator?
  • How do you multiply 9 times 3333, 444, 666666, or 88888 without a calculator?
  • Staff Review

    • Currently 3.0/5 Stars.
    This lesson explains a very useful tactic that many kids learn in elementary school, how to multiply by 9 with your fingers. Also, different methods of multiplying by 9 are shown that do not involve using your fingers. One pattern that is pointed out is that the product of 9 times a single digit number gives a first digit of one less than the number you are multiplying by and a second digit that is 9 minus the first digit. Also, multiplying 9 by a multi-digit number where all digits are the same is explained.
  • ktoluv

    • Currently 5.0/5 Stars.
    very knowledgeable
  • jenmaths

    • Currently 3.0/5 Stars.
    It is very knoledgeable, but it doesn't tell that how to calculate 9 x any 3 different nos. (eg.108).
  • student 101

    • Currently 5.0/5 Stars.
    this really helped me learn my math teacher couldn't teach that