0

99 x 12 = (99)·(12) = (90 + 9)·(10 + 2)
= 9x100 + (   )x10 + 9x10 + 18
= 900 + (   )x10 + 90 + 18 =     1188

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11

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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