- --- In MentalCalculation@yahoogroups.com, "tradewebhosting"

<tradewebhosting@...> wrote:>

Here's what Javi was getting at:

> How did you come to 17 x 172 = 289 x 10 is there some quick way.

>

> Mark

>

>

> Yes, i know its late , but i read the last messages now.

>

> I prefer this way : In 34 x 86 I hear "seventeen , seventeen.." ,

>

> i.e. 34 x 86 =

>

> 17 x 17 2 =

>

> 289 (x 10) + 34 = 2924

>

> Best wishes.

>

> Javi.

34 is a multiple of 17. (2x17)

86 is CLOSE to a multiple of 17. (5x17 + 1)

So 34 x 86 = (2 x 17) x [(5 x 17) + 1]

= [(2 x 17) x (5 x 17)] + [(2 x 17) x 1] = 2x5x17x17 + 34

=[10 x (17^2)] + 34 = 2890 + 34

Does that clear things up?

Al Stanger - In fact, since the ratio first digit:second digit in the first number (3:4) is the same as the ratio second digit:first digit in the second number (6:8 = 3:4) then both figures can be reversed.

Therefore the answer is the same as 43x68, and the sum can be negotiated this way if that's easier.

Andy

----- Original Message ----

From: Trade Web <tradewebhosting@...>

To: MentalCalculation@yahoogroups.com

Sent: Saturday, 16 June, 2007 6:41:06 AM

Subject: Re: [Mental Calculation] Re: 34 x 86

34 x 86

this is the way I do it as a beginner.... .

I put the

34 (over the eighty six)

86

then I multiply

6 x 4 = 24

then I add 6 x 30 = 180

so then I get 204

then I add 80 x 4 = 320

so then I get 524

then I multiply 80 x 30 and get 2400

and add it to 524 and get

2924

thats how I multiply 2 x 2 digit numbers.

If you need to reach me by instant messenger (sign up)

AIM: vfuturist

Skype.com : visionaryfuturist

--------

Affordable Web Hosting Solutions

http://www.1st- amendment. org

------------ --------- --------- ---

Get the free Yahoo! toolbar and rest assured with the added security of spyware protection.

[Non-text portions of this message have been removed]

___________________________________________________________

Yahoo! Answers - Got a question? Someone out there knows the answer. Try it

now.

http://uk.answers.yahoo.com/

[Non-text portions of this message have been removed]