YOUR AD HERE
|You are HERE >> Mathematics: Multiplication : Grades 4 and 5|
2 by 3 (or more!) digits
July 10, 2002
taken from the print ready worksheet found at http://www.lessontutor.com/jmmath.html
First off - always write these 'big' multiplication questions like the example (up and down), NOT like this: 367 x 24 (side by side). Sometimes this will mean doing the figuring in the margin of your worksheet page. One of my most fondly remembered math teachers had us draw a 2" inch line down the right hand side of every page of paper we used for math - just for this purpose. Alternatively, you could use a separate piece of paper. If it is for a test, be sure that all of your workings are well labeled, attached and submitted.
Secondly - If you have a choice (and you usually will), always put the bigger, or longer, number on the upper line. We both know that it does not matter the order in which you choose to work - anything times something will give you the same result as something times anything.
Thirdly - as
long as you
know your multiplication tables from zero to 9, you'll never have any
with these sorts of questions - regardless of how many digits are in
one. Here's how to do it. Step by step and line by line. Line dancing
Step 1: On the
below the question, work from the right hand side to the left, and make
little bitty notes as you go. I would be thinking and saying in my head
the following as I worked...
Multiply the 4
by the number in the 'tens' column - in this case the 6.
Step 3: 4 times 3 is twelve. Add the 2 carried over to make 14. Write the 14 in front of everything since there are no other numbers to work with for the moment.
Step 4: We'll
the entire top number (367) by the 2 in the tens column below, using
same right to left procedure including carry overs. But we have
finished working in the 'ones' column so we'll shift our
over one spot. You could put a mark of some description under the 8 in
the answer to block it off, but practice will have you doing the shift
automatically. It will look like a staircase when you are done.
Step 5: 2
times 6 is 12.
Add 1 is 13. Print the 3 under the 4 in
hundreds column and carry the one (1) to
the thousands column.
Step 6: 2
times 3 is 6,
add the one to equal 7. Place this in the
thousands column. Draw a line under the entire number.
Step 7: You're
done! Just easy stuff left - add the colorful 2 rows of numbers,
the ones from the original question. That means the 1468 and the 734*
- there is always NOTHING in the second row ones column.
If you are
going on to
multiply any number of numbers by larger ones, keep dancing one step to
the left for every number you are multiplying by. It will never matter
if these numbers have 2 or twenty columns, it will be done the same way
every time. Here's a picture to show you the stair
pattern I was telling you about earlier. Even if those numbers
Now go ahead and print the worksheet at http://www.lessontutor.com/jmmath.html and play away! Colours not necessary but use them if it helps you to see the columns more clearly
Legal & Privacy Notices