Math Is Fun Forum

Yes. That is correct.

Now let us go back to the original question:  Calculate  40 %  of  60.

Can you see what to do next ?

Right. Copy and complete the following:

40 divided by 10 is ...................

100 divided by 10 is .................

Right there are two approaches you could use. You could cancel down the fraction which I suggest you do in this case.

You could also do the division  40 divided by 100 to get a decimal which I would do if I were doing a problem like
that and allowed to use a calculator. However most maths students can do this in their head because as it happens
the numbers are nice round figures.

I suggest you cancel down the fraction first. However you may wish to look at what the calculator gives you as well.

Yes your post  #721 is correct.

So this fraction (35/1) is actually a whole number. It is simply 35 because any number divided by 1 is the number itself.

So 35 divided by 1 is 35.  So (35/1) = 35 also.

Right I will now give you a similar problem. See if you can work it out.  What is 40% of 60 ?

Have you got a calculator handy?

If so how about you type the division  70 divided by 2 into it. What do you get?

What does this tell you about the fraction  (70/2)  ?

Right here is what I was trying to get you to work out:

You have worked out that 50% = (50/100) = (1/2)

We need 50 %  of  70.

So this is the same as:  (1/2) x 70

Which is:   (1/2) x (70/1)

Using the fraction multiplication rules:

This is:  (70/2)

In this case because the number 70 was a whole number we did not really need to convert it into a fraction,
but if we use fraction multiplication then you know how to multiply a fraction by a percentage as well.

Yes this is correct so let us consider a problem involving 50 %

I need to calculate  50 %  of  70.  How could I do this ?

The reason why I have given us another look at fractions is that any percentage can be re-written as a fraction
with 100 as the denominator and cancelled down if appropriate.

So let us say that the percentage is 50%

We can write this as:

Can you see how we could cancel or simplify this fraction ?

Good you have got the hang of it. You can use \times to give an x
I know what you mean, but some people could argue that you have used 'x' in the sense of the letter here.

More importantly the denominator is still wrong.

5 x 7 is not 25 either.

Percentages ... but fractions were necessary for my explanation to make sense.
Every fraction can be written as a fraction with 100 as the denominator and is therefore a percentage.
So percentages can be converted into a fraction with 100 as the denominator (and cancelled if appropriate).

If you multiply by a percentage then it solves a problem in the form " A% of a number ".

You could re-write this as:  (A %) x (number) = (A/100) x number = (A x number) / 100

Mandy I recommend that you look through this entire page again I have updated some of my posts to improve readability.

Right I will give you a few fraction multiplication problems. Remember not to confuse adding and multiplying fractions.

Cancel or simplify as far as possible.

(At the time of posting I was unable to use Latex to display things like this in a good readable fashion
I have now been taught by Bob to do this properly. If you look further back, Mandy, you will find that
I have gone through it and tidied up the earlier fractions. They will hopefully be easier to read.)