Children are often confused and mystified by the need to
carry numbers in addition and multiplication. Here's how to
unveil the secret and make it simple!
!! Steps !!
!! Addition !!
* Have the child learn (and memorize) the basic addition facts.
Write out a math problem with two digits on the top and bottom.
Draw a line between the "units" and the "tens" column. It is not
important for your child to already know how to do two unit
addition.
Ask the child to answer the units column first, placing both
numbers in the correct (lower) positions. Do *not* have them put a
"1'' over the numbers, yet.
Ask the child to answer the tens column next. Make certain the
child places the digit(s) in the correct position (no digit should
be in the units column.) If they are confused, cover up the units
column. Have the child write the number(s) underneath the number
already written in the "tens" column from the "units" column
addition. Tell the child that the problem is not finished.
Review what you have completed so far.
* If you were using the example above, you might say, "We're almost
done. You did seven plus five equals twelve. *Good.* Four plus
three equals seven. *Correct*. Notice that the four and the three
are in the tens position, so you are really adding forty and
thirty."
Explain that some addition still remains. Have the child bring the
amount in the units column down to the bottom. Point to the
numbers in the "tens" column and ask the child to add them up.
* Make certain that the child is comfortable with this before
proceeding. By now, the child should already be familiar with the
communitive law of addition or (at least) know that the order of
addition is unimportant.
Tell the child that, instead of writing the "1'' under the tens
digit, they are to place the "1'' over the "tens" column.
* Ask the child to add the "1'' to the top number of the "tens"
column; then add the bottom number to that sum. Tell the child
that this is a shortcut we call "carrying".
!! Multiplication !!
This is a more complicated version of the method used in addition. A
fringe benefit of this method is that it reveals why estimation works.
Before you begin,
* Make sure the child already knows the basic multiplication tables.
Teach the child how to handle multiples of ten; we see this as
zeros on the end of a number.
Simply put: Anytime you multiply by a number with zeros on the end
(like 120 x 160), you add the number of zeros to the end of the
product.
120 x 160 becomes:
12 * 16 = 192
Place the two zeros on the end (One from 120 and another from 160)
= 19,2*00*
! Start With A One Digit Times Two Digit Multiplication Problem. !
Place column lines on the paper and make sure the digits are
properly placed.
Multiply the Units column and place the answer in the correct
columns. Before multiplying the Units column by the Tens column,
discuss the implications.
* Remind the child that the units column has already been
multiplied. Tell the child that when you multiply the units
column by the tens column it's like multiplying something with a
zero on the end.
Place a zero (0) in the units column *underneath* the first answer.
Multiply the Units column by the tens column and place the answer to
the left side of the zero (it will be underneath the first answer).
Have the child add the numbers together.
* Do not continue until the child can manage any problem of this
type (1 x 2)!
! Continue With A Two Digit Times Two Digit (2x2) Multiplication
Problem. !
Most children have no idea why their teacher skips a space on the
second line of "conventional" long multiplication.
Have the child complete the problem with the bottom tens digit
hidden (at first).
* Remind the child that he/she placed a zero in the right column
before multiplying a unit column by a tens column.
* Reveal the hidden digit and show the child that he/she will be
multiplying a unit by a tens digit again. Mark the two
multiplications (which will look like a big X).
Again, have the child place a zero(0) in the right hand column and
answer the units x tens multiplication to the left of the zero.
Discuss multiplying the tens by the tens column. Show the child that
this is like multiplying by 100. Have the child place zeros in the
two right columns and place the product to the left.
Have the child do the addition to finish the problem.
! Put It Together With Unit Times Two Digit (1x2) Multiplication !
This time, instead of writing the tens digit (from the unit x unit
product) under the line, write it ABOVE the tens digit column.
* Have the child compare this to carrying in addition.
Have the child do the units times tens multiplication; have the
child add the carried number to the product and write the number to
the left of the units digit already present.
* The child should become proficient at this before proceeding.
! Complete The Process. !
Add a tens digit and have the child cross out any carrying that has
already taken place.
Have the child treat the tens digit like the other one times two
digit work. Remind the child of the zero in the right column.
* This would be a good time to tell the child that the zero in the
right hand column is not necessary, but it won't hurt if they
leave it.
* Have the child finish by doing the addition.
!! Things You'll Need !!
* Paper and pen
!! Related WikiHows !!
* How to Understand the Concept of Zero ( 0 )
* How to Count to 99 on Your Fingers
* How to Add Numbers (Using the Count to 99 on Your Fingers Method)
* How to Teach a Young Child Beginning Math Skills
* How to Add Math Symbols in Online Assessments
!! Article Tools !!
* Read on wikiHow
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