Video: GCSE Mathematics Foundation Tier Pack 2 • Paper 2 • Question 2

GCSE Mathematics Foundation Tier Pack 2 • Paper 2 • Question 2


Video Transcript

Write nine over 40 as a decimal.

To convert a fraction into a decimal, we need to remember that the horizontal line in the fraction means divide. So nine over 40 means nine divided by 40. As we do have access to a calculator in this paper, we can just type this sum into our calculator and it gives 0.225. We don’t need to round this answer in any way. So our final answer is 0.225.

Now, remember this is a calculator question. So the method that we’ve used is perfectly fine. But suppose we didn’t have a calculator and we needed to convert nine over 40 into a decimal. We’d need to think of how we divide nine by 40 without a calculator.

As 40 is equal to four multiplied by 10, to divide by 40, we can therefore divide by four and then divide by 10. To divide nine by four first of all, we could use a short division method.

Four goes into nine twice with a remainder of one. So we have to add a decimal point and a zero after it and then carry the one into this column. Four goes into 10 twice with a remainder of two. So we have to add another zero after the decimal point and carry this remainder of two. Four goes into 20 five times with no remainder. So our division can stop here. Nine divided by four then is equal to 2.25.

Remember then we wanted to divide by 40. So now, we need to divide this answer by 10. When we divide a number by 10, it gets smaller. And in fact, to divide by 10, we can keep the decimal point fixed and move all of the digits one place to the right. This gives 0.225, which is the same as the answer we found when doing the division on our calculator.

The key point that you need to remember in this question is that that horizontal line in a fraction means you have to divide the number on the top, the numerator, by the number on the bottom, the denominator.

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