0

87 x 19 = (87)·(19) = (80 + 7)·(10 + 9)
= 8x100 + 72x10 + 7x10 + (    )
= 800 + 720 + 70 + (    ) =     1653

0

61

62

63

64

65

66

67

68

69

70

  1 of 20

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