Picture of How to multiply decimals
My mum's a teacher and she found thid really cool way of multiplying decimals in a teaching book. In the book it calls it 'Italian'.
Here goes...
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Step 1: Table

Picture of Table
In this example, the sum is 35.8 times 4.6
Set out a rectangle like this:

(The dots are decimal points)
(The diagonal lines are important)

Step 2: Tens

Picture of Tens
Multiply the numbers across so 3 times 4 is 12 and the tens digit is 10, so you write 1.

(If the product of the two numbers is less than 10, leave this half blank)

Step 3: Digits

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Now, you must add the digits.

Step 4: Magic!

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Add the up numbers diagonally. If the sum is over 10, carry one to the next sum to the left, if it is over 20, carry two to the left, etc.

Step 5: Decimal point

Picture of Decimal point
Now, to find the decimal point, find the line where both decimal points join up and go along the line.

So the answer is 164.68!

Try with other numbers and enjoy "cheating" on your maths questions.
STEMsheets11 months ago

Very interesting, thanks for sharing this technique. This website has some multiplying decimals worksheets to practice with: http://stemsheets.com/math/multiplying-decimals-worksheet-horizontal

maxyor3 years ago
YOU NEED MORE STEPS and examples

HMice3 years ago
Chaucermeow4 years ago
"Now, you must add the digits."

I am not seeing any addition in this particular step.
LiLGq4 years ago
i dont understand.....
NatNoBrains (author)  LiLGq4 years ago
nfk114 years ago
wow this is hard for me because im in 5th grade
MCzone4 years ago
Explain the *pundent* square for integers
NatNoBrains (author)  MCzone4 years ago
My teacher taught me this for mulitpying and dividing integers. example one positive and one negative make a negative, just follow the chart.
Punnett sqare.png
cokecola4 years ago
I think it's COOL!
NatNoBrains (author)  cokecola4 years ago