Want to be able to multiply any numbers between 11 and 19 in your head?
Then do this:
Example 19X18
Place them on top of each other in your head
19
18
Then create an Africa shape to cover the digits so you have
19
8
Add 19+8=27
Add a 0 to multiply by 10=270
then multiply the covered lower digit (8) by the number above it (9)
9x8=72 and then add that to the 270
270+72=342
----------------------------------------------------------------------
13X17
13
7
=20
adding a 0 that becomes 200
3X7=21
total is 221
View the Commer resto thread here http://66.129.69.181/forum/topic.asp?TOPIC_ID=3555 And more pics here: http://s786.photobucket.com/albums/yy149/bazil1972/
Then do this:
Example 19X18
Place them on top of each other in your head
19
18
Then create an Africa shape to cover the digits so you have
19
8
Add 19+8=27
Add a 0 to multiply by 10=270
then multiply the covered lower digit (8) by the number above it (9)
9x8=72 and then add that to the 270
270+72=342
----------------------------------------------------------------------
13X17
13
7
=20
adding a 0 that becomes 200
3X7=21
total is 221
View the Commer resto thread here http://66.129.69.181/forum/topic.asp?TOPIC_ID=3555 And more pics here: http://s786.photobucket.com/albums/yy149/bazil1972/