# Thread: How do you work out percentages without a calculator?

1. ## How do you work out percentages without a calculator? var addthis_config = {"data_track_clickback":false};

I have a test for a job coming up and they require you to work out gross profit and percentages without using a calculator.. I have always used a calculator for things like this. Please please can some one help and give me some tips to do this. I really want this job and this is the final part, and if I fail this I don't get the job.
I would be so so grateful

2. it seems that the test was for accounting department

for example
gross profit=10% of sales
sales=40 000

find the gross profit
10%*40000
=10/100 * 40000
=10*400
=4000

3. just do your keystrokes on paper
ex: 22.3% of \$5609.00
.223 * 5609
\$1250.81

4. For any percentage the basic rule is the difference between the two values divided by the original value multiplied by 100.

For example, if the original value was 10 and it changed to 5, 5 divided by 10 multiplied by 100 = 50%

It has changed by 50%

5. Hi,
Here is a link to a page that explains it and gives an example.

Another example is what is 6 as a percentage of 24? You take the 6 and divide 24 into it, that is you calculate 6/24 which is 1/4. So that is the answer as a fraction. Now to get the percentage you multiply by 100 which is 100 x 1/4 = 100/4 which is 25%.

Percentages are simple once you know that 'cent' means one hundred and per cent (percent) means per hundred. So percentages are a way of expressing a number normalised to one hundred which is why you multiply by one hundred which looks an odd thing to do otherwise.
Bill

6. A simple way to figure out percentages is to make everything out of 100 for example...

1/5 = 2/10 = 20/100 = 20%

1/20 = 5/100 = 5%

7. Not quite sure what percentages you are likely to have to calculate but there are certain values that you can workout fairly readily .

1) 10 % This is trivial. Just move the decimal point one place to the left to get the 10% number and, if you are increasing by 10% then add it to the original number or if decreasing by 10 %, subtract it.

2) 15 % Recognise that this is 10% plus 5% and 5% is one half of 10%. So, using simple numbers

15% of 100 is 10 % plus half of 10%. So, 10% = 10, 5 % = half of 10% = 5 giving 15

15% of 1200 = 120 + 60 [half of 120] = 180 Get the idea.

3) 12.5% of something = 10% + a quarter of 10%.
So, 12.5% of 600 = 60 + 15 [one quarter of 60] = 75

4) 17.5% = 10% + 5% + 2.5 % [These are all half of each other]

So, 17.5% of 480 = 48 + 24 + 12 = 84

Try to find ways of breaking up the % number into these various divisions and with a bit of practice you can do these mentally. Hope this helps. Good luck with the job!!

8. Elementary language:

To find out the percentage of a number move the decimal place to the left two places then multiply.

Ex. 20% of 110 = .20 x 110 = 22

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