Coffee Math:

Methods, Tips And Tricks Series.

By Puwork UtaraMay 2011

Multiplying 2 Numbers

Close to 100

They are in the base 100. Hence the reference point

(base) will be 100.

88 98 = ______X

Both numbers

are close to 100

but less than 100

88 98 = ______X

88

98

100

100

+12

+ 2

88 98 = ______X

88

98

100

100

+12

+ 2

88 - 2( ) 100X = 8600Either

98 - 12( ) 100X = 8600Or

88 98 = ______X

88

98

100

100

+12

+ 2

88 - 2( ) 100X = 8600Either

98 - 12( ) 100X = 8600Or

12 2X = 24And

88 98 = ______X

88

98

100

100

+12

+ 2

88 - 2( ) 100X = 8600Either

98 - 12( ) 100X = 8600Or

12 2X = 24And

+ =24Last 8600 8624 #

102 104 = ______X

Both numbers

are close to 100

but more than 100

102 104 = ______X

102

104

100

100

- 2

- 4

102 104 = ______X

102

104

100

100

- 2

- 4

102 + 4( ) 100X = 10600Either

104 + 2( ) 100X = 10600Or

102 104 = ______X

102

104

100

100

- 2

- 4

102 + 4( ) 100X = 10600Either

104 + 2( ) 100X = 10600Or

-2 -4X = + 08And

102 104 = ______X

102

104

100

100

- 2

- 4

102 + 4( ) 100X = 10600Either

104 + 2( ) 100X = 10600Or

-2 -4X = + 08And

+ =(+08)Last 10600 10608 #

97 102 = ______X

One of the numbers

is less than 100 and

the second number

is more than 100

97 102 = ______X

97

102

100

100

+ 3

- 2

97 102 = ______X

97

102

100

100

+ 3

- 2

97 - ( -2)( ) 100X = 9900Either

104 - 3( ) 100X = 9900Or

97 102 = ______X

97

102

100

100

+ 3

- 2

97 + 2( ) 100X = 9900Either

104 - 3( ) 100X = 9900Or

+ 3 (-2 )X = - 06And

97 102 = ______X

97

102

100

100

+ 3

- 2

97 + 2( ) 100X = 9900Either

104 - 3( ) 100X = 9900Or

+ 3 (-2 )X = - 06And

+ =(- 06 )Last 10600 9894 #

END