To be slightly horrified at how poor my basic skills are?

[primrosesandmaths]

In my professional, graduate profession, I have just been told I have to work out something as a percentage.

I have no idea how to do it.

I shall google - it isn’t an advice thread as such, but my maths is just dire and I can’t help wondering if this is common or whether I am an imposter in my role.

Google. I spend a lot of time googling 'what % increase is x from x'

There's only so much brain space isn't there? The bit that used to be filled with percentages is probably full of exciting things like mean planning and remembering to pick the kids prescriptions up.

X just means "number we don't know" so stands as a substitute for "what" or "the number of apples" or whatever the question is asking about.

Sorry just caught up with thread and realised i'm a bit behind the times as everyone is into the specifics of the problem at hand. You aren't stupid OP. I spent YEARS of my primary education having this stuff drilled into me. The french system is shit at imparting any kind of creative thinking, but really excellent at basic skills, or at least it was 35 years ago!

What is 7 out of 25 as a percentage

7/25 then multiply by 100 (=28%)

Basic rules you may not know:

1. A whole number can be rewritten as a fraction 6 = 6/1
2. To multiply 2 fractions you multiply the tops (numerators) and multiply the bottoms (denominators)

7/25 x 100 = 7/25 x 100/1 = (7x100)/(25x1) = 700/25 = 28.

Any help?

Right, so

15 out of 30 I guess must be 50%? But how

15/100 is 1500

Oh, I give up

No, I don’t understand why fractions are coming into it I’m sorry; I’m rubbish!

% increase means x 100%

percentages are based on original amounts not the new amounts.

I can't remember how to do multiplication and addition on paper like I used to when I was little.

Not addition, Division!

The way I think of it is that:

performing 12 divided by 25 tells you what fraction of 25, 12 is, on a scale of 0 to 1.

so 25 divided by 25 gives you 1, so 25 is all of 25.
0 divided by 25 gives you 0, so 0 is none of 25.

5 divided by 25 give you 0.2. so a small proportion of 25.

12 divided by 25 give you 0.48. This is nearly 0.5 so sanity reins and 12 is nearly but not quite, half of 25.

Everything after that is determining how you want to express the proportion. 0-1 is a perfectly reasonably scale! But many people prefer a 0-100 scale (also know as percentage :) ).

So once you have the 0-1 answer, you simply multiply by 100 to find out what the same proportion is when take in the range 0-100.

In this case it is 48 out of a 100 or 48%.

12 out of 25 as a percentage.

Well, as a rough ready reckoner, 50% of something is half.

Half of 25 is 12.5. So 50% of 25 is 12.5.

The answer will only be slightly less than 50%. You have a ball park figure to compare any result you get.

12 divide by 25 = 0.48

0.48 times 100 (because per cent means by the 100) = 48%

Or, conveniently, 100 = 25 x 4.

12 x 4 = 48.

15/30 x 100

= 1500/30 = 50%

15 divided by 30 can be written as a fraction 15/30

The / means divide * means multiply (I have been using x as we aren't doing algebra when it gets confusing, except MrsHathaway did earlier, so you are probably getting extra confused by us both trying to help you)

Seven pages of lovely people trying to help and I’m still unable to do it

I am beyond help.

So 15 divided by 30 is 0.5. On a scale of 0-1, 0.5 is the middle point and so 15 is half of 30 (as you suspected :))

to rescale this from 0-1 to 0-100 you multiply by 100.

Hence 15 out of 30 becomes 50%....as 50 is the midpoint between 0 and 100.

7 / 25 = Seven divided by Twenty Five

One percent = One over One Hundred = 1/100

So to work out 7/25 as a percentage you need to make an equivalent fraction over one hundred.

So to simplify: 1/2 = 50%

How do we work that out?

100 (for the %) divided by the bottom of the fraction (2 in the example here) gives 50 - so that's our multiplier.

Then we can multiply the top and the bottom of the fraction by 50 to get our equivalent fraction over 100: 1 x 50 = 50 and 2x50 = 100, so our equivalent fraction is 50/100 which we can then see is 50%.

We can then do the same thing to your example:

100 divided by 25 = 4 so our multiplier here is 4.

Multiply on the top and bottom to get our equivalent fraction (essentially multiplying by 4/4) 7x4 = 28 and 25x4 = 100, so our equivalent fraction is 28/100 which we can then see is 28%

Does that make any sense?

This is a fab course in basic maths: mathschoices.open.ac.uk/mu123

prim you totally are not beyond help...though god knows an internet forum may not be the easiest mode for communicating maths concepts.

Stick with what you know! 15 is half of 30....50 is half of a 100....so 15 out of 30 should be 50%....and it is :)

You aren't beyond help.
You need to either watch a good video, or get someone to sit with you to see what you do or don't understand and go from there.
If your understanding of fractions is a bit ropey, then percentages are going to feel harder.
It is much easier to help someone with a pen and paper than online.

1% = 1/100
5% = 1/20
10% = 1/10
20% = 1/5

The higher the percentage, the smaller the number in the fraction.

15 divided by 100 is 0.15
Multiply by 100 and you have 15%.

You did multiplication instead of division
In your example.

I failed my GCE maths first time round but I can easily work out percentages, it was just elementary stuff when I was a child. Even so if you have (old fashioned) a calculator and know what 100% is surely anyone could work out what to do next?

15 out of 30 is a fraction. That's what fractions are. 9 out of 10 cats prefer Whiskas is a fraction. 6 fish fingers divided by 4 DC is a more complicated fraction.

Usually we write 15 out of 30 as something like 15/30 which means 15 divided by 30.
so if you typed in on your calculator 15÷30 it would give 0.5
0.5 is another way of saying "half"

To get that as a percentage, you then multiply by 100 and you get 50%

And that makes sense because you know that 15 is a half of 30, and your final answer is 50% which is a half of 100.

To answer your earlier question -
/ means divide
x means times

7 divided by 25 = 0.28

Then multiply 0.28 by 100 to get the percentage = 28%

Prim - either find someone in real life who's good at explaining things and get them to explain it several times until you understand what they're saying

or - look at all the people trying to explain it on this thread, pick one of them and look at all their posts, and ignore everybody else's. If that doesn't work, pick someone else and read all their posts.

I'm really impressed with how hard you're trying with this. You will get there in the end, but all of us falling over ourselves in our eagerness to explain isn't helping you (and I'm guiltier than most)

I also like the National Numeracy Challenge website and help sheets. I was lucky though - at my primary school in the 70s teachers weren't actually allowed to teach grammar and arithmetic in "old-fashioned ways". My lovely teacher used to lock the door (yes, really) and have us reciting times tables, doing mental arithmetic, spelling things and carrying out elementary parsing. She used to make it a competition so it was also fun. Later on at high school when they started streaming us for English and Maths in third year, nobody from the other class at my primary school was in the top set, whereas quite a few of us from my class were.