Pre Algebra Multiplying Larger Numbers
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Big Time Multiplying
Multiplying Larger Numbers

 
 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 any-ty) 
 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

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