0

91 x 72 = (91)·(72) = (90 + 1)·(70 + 2)
= (   )x100 + 18x10 + 7x10 + 2
= (   )x100 + 180 + 70 + 2 =     6552

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FirstOuterInnerLast

 

Level

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2

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How Many

5

10

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30

50

  

FOIL method @

 

Example >>>

 34 x 52 =  (30 + 4)·(50 + 2)

 

 

 

  

First

(A + B)·(C + D) = AC + AD + BC + BD

= 30 x 50

= 1500

Outer

(A + B)·(C + D) = AC + AD + BC + BD

= 30 x 2

=     60

Inner

(A + B)·(C + D) = AC + AD + BC + BD

= 4 x 50

=   200

Last

(A + B)·(C + D) = AC + AD + BC + BD

= 4 x 2

=       8

 

 

    

 

  

 

= 1768