0

155 x 40 = (155)·(40) = (150 + 5)·(40 + )
= 60x100 + (   )x10 + 20x10 + 0 =
= 6000 + (   )x10 + 200 + 0 =     6200

1

71

72

73

74

75

76

77

78

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80

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FirstOuterInnerLast

 

Level

1

2

3

4

How Many

5

10

20

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