



Multiplying
small numbers together 


lets
you practice learning the times tables. 


But
to multiply big numbers together, 


you
need a plan. 





Example 











You
do this one in steps. 





First
Multiply 7 times 2.
7 + 7 = 14
Write the 4 at the bottom of the column.
Put the 1 (the 10 that is) at the top
of the next column. 







Now
Multiply 7 times 5 and then add the 1.
7 + 7 + 7 + 7 + 7 = 35.
35 + 1 = 36
Write the 6 at the bottom of the column.
If we had another column we would put the 3 (the 30 that is)
on the top and go on,
Since we're out of numbers,
write the 3 down too and we're done. 







Here's
how this works. 


Take
the number on the bottom and multiply it times each number on
top 


going
right to left. 


When
you get ten (or twenty or thirty or anyty) 


put
it on top of the next column. 


If
there is no next column, write it at the bottom. 


You're
done! 





Example 











First
multiply 6 x 8.
6 + 6 + 6 + 6 + 6 + 6 + 6 + 6 = 48
Write the 8 at the bottom of this column.
Put the 4 on top of the column to the left 







Now
Multiply 6 times 2 and then add the 4.
6 + 6 = 12.
12 + 4 = 16
Write the 6 at the bottom of the column.
If we had another column
we would put the 1 (the 10) on the top and go on,
Since we're out of numbers,
write the 1 down too and we're done. 







copyright 2005 Bruce Kirkpatrick 
