More On ShortCuts In Multiplication

MORE ON SHORTCUTS IN MULTIPLICATION


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Multiplying Two Numbers Whose Sum of Their Last Digits is 10  and Their Other Digits are the Same


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Example One :  34  X   36


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Solution by steps :


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1)  Multiply the first digit by one more than itself  :   3 X  4   =  12


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2)  Multiply the last digits  :     4  X  6   =     24


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3)  Combine the answer            1224


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Short way   :     3 X 4   =  12,     4  X    6   =   24     Answer:   34  X   36   =   1224


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Multiplying Two 2-digit Numbers Whose Sum of Their First Digits is Ten  and Their Last Digits are the Same


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Example  One :      64  X  44


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Solution   by steps :


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1) Multiply the first digits and add a last digit:  (6 X  4 )  = 24  +  4   =   28


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2)  Multiply the Last digits :   4 X  4  =   16


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3) Combine : 2816


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Short way  :   6 X 4 + 4  = 24 + 4 = 28,   4 X 4  =   16


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Answer  :      64  X  44  =  2816


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Try for yourself the following items using shortcut :


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1)    35   X   75


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2)    43   X    47


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3)    86    X   26


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4)     52   X   58


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5)      39   X   79

Answers  :


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1)  2625    2)  2021    3)  2236   4)  3016  5)  3081


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SOURCE :


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21ST CENTURY MATHEMATICS 6

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Comments 16 comments

Moon Daisy profile image

Moon Daisy 7 years ago from London

Wow, that's great! I've never come across those before and would love to find out why they work. Maybe if I have time I'll try to work it out! :o)

Thanks, the shortcuts may come in handy with any future maths teaching that I do.


cristina327 profile image

cristina327 7 years ago from Manila Author

Hi Moondaisy. It is nice to hear from you again. Regards.


john 7 years ago

44*12

Look at the left side of the equation and think 4 x 1 is 4.

Keep this number in your head.

Next add up the digit 1 and 2 and think, 3 x 4 is 12. Combine the numbers 4 with the 1 in 12. Think 52, this is the partial answer.

End with 4 x 2 is 8. Place the 8 at the end of 52, for the answer 528

With practice you will be able to do this in seconds.

Of course for multiplying by 12 you could always just write down the first digit. (4) Double the same digit and add the rightmost number. 8+4=12. Carry the one to the first number for 52, and double and place the last digit (8). 528.

Or, you could double the entire number (44) to 88. Carry the 8 to 44 for 52, and place the 8. 528.


Jones 7 years ago

I solved every problem, it works GREAT! thanks a lot for your work.


kishore 6 years ago

Its not working for some problems like

52*58, 62*72 , 63*53 and some other problems.

Please help me.


bindiya Vig 6 years ago

i knw left multiplication only thanks for rhs mul


braica 6 years ago

thanks a lot


Sexy 5 years ago

like it


jacob 5 years ago

i don't get how you got the answers at the bottom


lucky 5 years ago

super


shankar 5 years ago

niceeeee


Somasis Mondal 5 years ago

it's a nice procedure...can u tell me short cut multiplication procedure of (3215*135)....please help me...


priyam 5 years ago

how to calculate 999*99*9 shortly......pls rply


rameshwar 4 years ago

it is super


roeun 4 years ago

how do we multiply this by shortcut way

9876*6742


sherrywin 4 years ago

salamats po//...

")))

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