How do you find out the percentage of something using a calculator?

Question

For example, something is $40 with 80% off.......I used the calculator and did 40X.80 and it came out to 32 and I did 40-80% and it came to $32 also. I know these aren't right though because 50% off of $40 is only $20. I don't need to know the answer really, just mainly how to get the answer. Thanks a bunch!

Answer 1

what you did was find 80% of 40

Since it is 80% OFF, you have to subtract that from 40

40 - 32 = 8

your other option is to change the percentage. Since it is 80% off - what you pay is 20%. 20% of 40 = 8

Answer 2

Percentages can be tricky... you have to be really careful that you are calculating the right value. To make matters worse, they aren't bi-directional (i.e. if x is 40% more than y, that doesn't mean y is 40% less than x for example).

"Percent" means, literally, parts per 100. So you have to be sure and write everything down carefully.

We usually have two values when dealing with percentages, plus the percent itself. So we have initial value, final value, then a percentage.

In your example, you say "something is $40 with 80% off", so we know the final value ($40) and the percentage (20%... since it is 80% off, this leaves 20%), and we need to know the original or initial value.

In general, percentage problems look something like:

inital * percent = final

The tricky part is often figuring out how to determine "percent", because as in your example above, it isn't always given directly.

We knew the final price was 80% off the original price, so we have to calculate that this means the final price is 20% of the original.

initial * 20% = final
initial * 0.2 = 40
initial = 40 / 0.2
initial = $200

Now let's check!

80% off of $200 would be what? 200 * 0.8, or 160.

$160 off of something $200 would leave $40. So we were right!

Of course, your problem could be read another way: the initial cost is $40 and it is then 80% off. In this case, we know that 20% will remain, but now $40 is the initial cost. This is much easier to calculate:

initial * percent = final
$40 * 20% = final
final = 40 * 0.2
final = $8


I hope this helps some. Just be careful and follow these steps and hopefully it will become easier and make some sense. And don't worry, I've been doing math a long time and still screw up percentage problems sometime :)

Best of luck!

Answer 3

Most calculators have a button labeled "%" . So if you want to know what % 5 is of 6 simply type in 5, press the divide button , press 6 then press the % button. The answer will be 86.3333333.

If your calculator does not have a % button, then press 5, press the divide button, press 6, press multiply button, type in 100 and press = button.

If you want to know what an item selling for $40 will cost you if it is being sold at 80% off, it is easier to subtract 80 from 100 and get 20%. Then multiply 40 by 20%= 40* .2 = $8.

I do not understand how you did 40 - 80% and got $32.
You correctly computed 80% of $40 to be $32. So $40 -$32 = $8.

40 - 80% means 40 - .8 = 39.2. It is a rather meaningless thing. What you really wanted was 40- 80% times 40 = 40 - 32=8.

Answer 4

$40 X .80 = 32
$40 - 32 = $8

Answer 5

You did it right the first time and then just forgot a little something...

When you want to take a percentage of something, say 80% you multiply the number by .8...

So.. $40*.8 = $32 this is correct

Now if you want to say that something 80% off of $40 you simply subtract 80% of $40 from $40...

so $40 - (.8*$40) = $40 - $32 = $8

therefore, 80% off of $40 is $8

Answer 6

$40 with 80% off

$40 x 80% = $32 (so $32 is the discounted given)

$40 - $32 = $8 (you just have to pay $8, this is after 80% off)

Answer 7

Your solution is correct

When you multiply 40 x .8 = 32 The same results can be obtained when upi selected 40 - 80% on your caculator.

Thirty two parts of forty 32 / 40 = .8 or 80 %

40 - 32 = 8

You pay $ 8.00

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Your example of 50 % off of $ 40 = 20 is correct.

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Answer 8

if it is $40 with 80% off that means that $40 = 20%

Then just use a ratio

($40 * 100%)/20% = 200$ for the item at full price.


if it is $40 at full price and 80% off then you just apply the ratio as

($40*20%)/100% = $8 at the discounted price.

Answer 9

40-80% comes out to 8 on my calculator.

Answer 10

Multiply by 0.80 is correct to calculate the amount that 80% represents. That is the discount, in dollars. Then subtract the discount from the price.