Education For All's focus

Education For All's focus

Help teachers, parents, students and education leaders understand how incorporating vedic math sultras/principles into math education can help improve students' math scores and appreciation of math.


Monday, February 14, 2011

How do I love thee? Let me count the ways... of solving 95 * 95

The famous quote can be borrowed on this Valentine's Day to look at the beauty of math. In life there are few problems that can only be solved one way, even though only one option may appear to us at first. It takes creativity to see potential solutions that are not obvious. If I am hiking and need water there are several potential options available besides for a body of water. Depending on your environment some creative options for getting water are cutting a green bamboo tree, melting non-salted snow or collecting morning dew with a cloth.

We can creative in solving math problems. Below are four different approaches to solving 10 * 11:
1) Add 10 to the product of 10^2
2) Use the multiply by 11 method
3) Subtract 11 from the product of 11^2
4) Double the product of 5 * 11

How many ways can we solve 95 * 95?
Reply back with how many, and which ways, you would solve the problem 95 * 95.

3 comments:

  1. Hmmm...I don't think I have the fastest way, but my instinct is to multiply 95 X 100 because that's easy (9500), and then subtract 95 * 5 (5 is the difference between 95 and 100). I'm able to pretty quickly figure out 95 * 5 by just multiplying 95 * 10 (950) and dividing it into two (475). So, 9500 - 475 = 9025.

    Again, probably not the fastest way. But it's a way. :)

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  2. Hi,

    I believe to the 4 listed methods of calculating 10*11 you can add

    5) Use the "multiply by 10" method.

    As to 95*95, there is at least one method common to squaring numbers that add in 5:

    a) drop 5 to obtain 9
    b) multiply 9*(9 + 1) = 90
    c) append 25: 9025

    For an explanation and other rapid math tips, see
    http://www.cut-the-knot.org/arithmetic/rapid/rapid.shtml

    ReplyDelete
  3. Make it (100 - 5)(100 - 5)
    = 10,000 - 500 - 500 + 25 (using "foil" from algebra)
    = 9,000 + 25 = 9,025

    ReplyDelete