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Multiplying
small numbers together |
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lets
you practice learning the times tables. |
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But
to multiply big numbers together, |
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you
need a plan. |
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Example |
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You
do this one in steps. |
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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. |
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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. |
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Here's
how this works. |
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Take
the number on the bottom and multiply it times each number on
top |
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going
right to left. |
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When
you get ten (or twenty or thirty or any-ty) |
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put
it on top of the next column. |
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If
there is no next column, write it at the bottom. |
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You're
done! |
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Example |
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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 |
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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. |
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copyright 2005 Bruce Kirkpatrick |
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