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esatpllana

Member

Registered: 2007-11-22

Posts: 12

Multiplying 2 digits by 45

nice trick here
if you don't have a pencil or pen or notebook near you ,you can multiply in ur brain
ok we start
take one number wit 2 digits example 25
and multiplying with 45 how?
the last digit of 45 multiply with 25 (5x25) equals 125 add the zero to the number 1250 and substract with number 125 (without zero) (1250-125) equals 1125.
Multiply 25*45 in ur note book to verify if is ok the result is 1125
ok thnx all bye

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MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: Multiplying 2 digits by 45

17 x 45: 17*5 = 85, then. 850-85 = 765. Yes!

Neat trick, thanks.

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esatpllana

Member

Registered: 2007-11-22

Posts: 12

Re: Multiplying 2 digits by 45

hehe yes!

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JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Multiplying 2 digits by 45

And now, allow me to present …

How to multiply by 55

Same, but you add the two numbers instead of subtracting them. Examples: 17 × 55 = 850 + 85 = 935; 25 × 55 = 1250 + 125 = 1375.

esatpllana

Member

Registered: 2007-11-22

Posts: 12

Re: Multiplying 2 digits by 45

wowwwowowwowowwowowo really good so nice thnx

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lester_day

Member

Registered: 2007-11-19

Posts: 4

Re: Multiplying 2 digits by 45

You may be interested in a book entitled: "Rapid Math ...tricks and tips" by Edward H. julius.
It contains numerous examples such as the ones you mentioned. Julius maintains that,  if you do the exercises in the book over the course of 30 days, you will dramatically improve the speed of your mental arithmatic.
                                lester_day

esatpllana

Member

Registered: 2007-11-22

Posts: 12

Re: Multiplying 2 digits by 45

"Rapid Math ...tricks and tips" by Edward H. julius where to find this book friend
I'm from Kosovo we can talk together my email [email protected] see you later

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iheartmaths

Member

Registered: 2008-01-08

Posts: 31

Re: Multiplying 2 digits by 45

And by 11
as in 25 x 11 =
take the first digit, which is 2 and write it down. Then add the first digit to the second digit, which is 2 + 5, which equals 7, so that now we have 2 & 7. Finally, take the last digit, which is 5, and write it down. So, 25 x 11 = 275
The good thing is that this method works for any number times 11, like 1,450,623. Just repeat the second step until you've done all the digits. So, 11 x 1,450,623 = 15,956,853

Last edited by iheartmaths (2008-01-13 10:06:18)

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esatpllana

Member

Registered: 2007-11-22

Posts: 12

Re: Multiplying 2 digits by 45

wow it's good thank you

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tereline

Member

Registered: 2008-04-25

Posts: 3

Re: Multiplying 2 digits by 45

.

I found an easy to follow video tutorial of the above mentioned speed multiplication with 11 .  The website below has other amazing tricks of faster mental math as well like finding the squares of numbers in your mind.  Check it out !!

Fast mental Math tricks n techniques ( secret ) to end daily mental math problems. Fun Mental Math for kids. Vedic Mathematics tricks website with math videos

Alyssa_96

Member

Registered: 2008-08-08

Posts: 4

Re: Multiplying 2 digits by 45

Nice Trick!!

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