Multiply two numbers involving decimals
Multiplying two numbers that involve decimals without using a calculator can seem scary, but there are incredibly easy ways to solve these problems.
Let's take this sum;
0.03 X 1.1
First, let's try and make the question easier by getting rid of the decimal points for now. If we move the decimal point along to the right, essentially multiplying by 10, until both our numbers are whole numbers, like so...
0.03 x 1.1 becomes...
0.3 x 11.
Which then turns into...
3. x 11.
... We can make the equation a lot easier. We need to remember how many decimal places each number had to begin with so we can get our answer later.
0.03 has two decimal places, and 1.1 has one decimal place, and once we add them together we learn that our answer will have three decimal places.
Now, we just work out our new equation...
3. x 11. = 33.
...And we take our answer, and we shift the decimal place (which always comes after a whole number) back however many times we moved it in the first place.
So, we backtrack with our decimal point three times, as the numbers we added together had three decimal places in total.
33 becomes...
 3.3
 0.33
 0.033
This handy trick should make multiplying decimals easy. Just remember to keep track of how many decimal places you move each number and the number of deciaml places together for the answer.
Follow the links below to see how this topic has appeared in past exam papers
AQA Unit 2 November 2011 (F)  Page 3, Question 3
AQA Unit 2 November 2011 (F)  Page 10, Question 12(b)
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