0

97 x 81 = (97)·(81) = (90 + 7)·(80 + 1)
= 72x100 + 9x10 + 56x10 + (    )
= 7200 + 90 + 560 + (    ) =     7857

0

1

2

3

4

5

6

7

8

9

10

  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