**
Maha's
NEW method for dividing decimals**

**
**

**Don was
helping Maha with problems she was having trouble with on the SSAT test. The
problem they looked at was: '16 is 25% of what number?' Don's first reaction was
to write this as 16 = 25%* ? One method Don had was 16'1/4 = 16*4/1= 64. Maha
knew that she should divide 16 by .25; she wrote
. They talked about the 'normal' way to do this: Move the
decimal point 2 places to the right in each number, so
would change to . Don made sure that Maha understood why this would give the
same answer. He showed her that ' = 30/40 because when you multiply the top and
bottom of a fraction by a number, say 10, to get
, and . Now what happens if you multiply a number by 1? It doesn't
change anything. So = = = = ; and by multiplying top and bottom by 100. That's why they taught
us to 'move the decimal 2 places to the right' (multiply top and bottom by 100)
- and make a whole number 25
outside the box.**

** **

**The above
was a little background to
Maha's method: **

**She took
and changed it to
, which is NOT the same problem any more. But with a little
discussion, she agreed that when she got her answer she would have to multiply
it by 100, because she divided 16 by 100 to get **
.16 **
. Maha tried the division on the
right below first, .1 ' .2 ; she added a couple of 0's to get .100 and
she put the decimal point in the answer above the decimal point below it. She
said 20 into 100 will go 5 times. So her answer was .5 . Don checked this with
strips (.2 of the 10x10 square will go into .1, ' or .5 times). They checked it
also by multiplying .5 * .20 = .100 = .1 .**

** **

**Maha then
did their original division,
above left, .16000 ' .25 = .64 (because 25 will go into 160 6 times,
then 25 will go into 100 4 times), then she multiplied .64 by 100 to get the
correct answer of 64. **

** **

**What Maha
did was very exciting, because she made up this new way to divide decimals, that
neither of them had seen before!!**

**
Fine job, Maha!!**

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