blocks|key|2409232|text|因为你想错了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2409233|你不收30美元，你收31.20美元。Paypal从中扣除交易费(2.9%25)，然后从结果中提取0.30美元：|2409234|++$31.20
*++0.971+(1+-+2.9%25)
++------
++$30.2952
-+$00.30
++------
++$29.9952|code-block|syntax|javascript|2409235|所以你必须颠倒这个过程，即在你的总数上加上$0.3，然后除以0.971。|2409236|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Because you're thinking about it the wrong way around.

You don't charge $30, you charge $31.20. Paypal takes the transaction fee (2.9%) off of that and then takes $0.30 from the result:

<pre><code> $31.20
* 0.971 (1 - 2.9%)
 ------
 $30.2952
- $00.30
 ------
 $29.9952
</code></pre>

So you have to reverse this process, i.e. add $0.3 to your total and divide by 0.971.

blocks|key|674562|text|你的函数看起来确实很奇怪。为了细分，PayPal收取固定利率的$.30，并增加2.9%25的交易百分比手续费。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|674563|其公式是将$.30相加，然后除以百分比差异(100%25+-+2.9%25)，这将得到PayPal实际减少之前的数量。|674564|function+memfees($amount)
{
++++$amount+%2B=+.30;
++++return+$amount+/+(1+-+.029);
}|code-block|syntax|javascript|674565|您可以根据自己的意愿对其进行舍入和浮动。|674566|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Your function does seem strange. To break it down, PayPal is charging a fixed rate of $.30, and adding a transaction percentage fee of 2.9%.

The formula for this is to add the $.30 and then divide by the percentage difference (100% - 2.9%), which will give you the amount prior to the actual reduction by PayPal.

<pre><code>function memfees($amount)
{
 $amount += .30;
 return $amount / (1 - .029);
}
</code></pre>

You can round and float that as you wish.

blocks|key|2313298|text|这里有一个很好的数学解释来解释这是如何工作的。我们有这个号码，x，我们想把它记在信用卡上。我们不知道这个数字是多少，但我们知道，当我们减去30美分，再减去x的2.9%25，得到y，这是我们带回家的钱的数量：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2313299|y+=+x+-+x+*+.029+-+.3|code-block|syntax|javascript|2313300|我们知道y，因为我们知道我们想要带回家的数量。比方说，我们想带回家100美元，然后y=100。但是x是什么呢？|2313301|y+=+x+-+x+*+.029+-+.3
y+%2B+.3+=+x+-+x+*+.029
+++++++++=+x(1+-+.029)
(y+%2B+.3)+/+(1+-+.029)+=+x
x+=+(y+%2B+.3)+/+.971|2313302|注意:因为x+-+x+*+.029可以被写成x+*+1+-+x+*+.029，所以所有需要做的就是使用分布式属性，我们提出了x(1+-+.029)|offset|length|style|CODE|2313303|所以我们想出了这个公式：|2313304|x+=+(y+%2B+.3)+/+.971|2313305|它定义了这个臭名昭著的数字x。同时，它回答了我们的问题:我应该收取多少金额才能支付交易费，而又不低于我们想要带回家的金额？好的，我们需要做的就是填入带回家的金额，即y：|2313306|x+=+(100+%2B+.3)+/+.971
x+=+~103.30|2313307|我希望这有助于澄清。|2313308|entityMap^0|0|0|0|0|5|C|M|G|1Q|B|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|16|8|@$M|17|N|18|O|P]|$M|19|N|1A|O|P]|$M|1B|N|1C|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1D|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|1E|8|@]|9|@]|A|$E|F]]|$1|U|3|V|5|6|7|1F|8|@]|9|@]|A|$]]|$1|W|3|X|5|D|7|1G|8|@]|9|@]|A|$E|F]]|$1|Y|3|Z|5|6|7|1H|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|11|$]]

Here's a good mathematical explanation of how this works. We have this number, x, which we want to charge a credit card. We don't know what this number is, but we know that when we subtract 30 cents and subtract 2.9% of x, we get y, which is the amount of money we take home:

<pre><code>y = x - x * .029 - .3
</code></pre>

We know y, because we know what amount we want to take home. Say, we wanted to take home $100, then y = 100. But what's x?

<pre><code>y = x - x * .029 - .3
y + .3 = x - x * .029
 = x(1 - .029)
(y + .3) / (1 - .029) = x
x = (y + .3) / .971
</code></pre>

Note: because <code>x - x * .029</code> can be written as <code>x * 1 - x * .029</code> then all need to do is just use distributive property and we come up with <code>x(1 - .029)</code>

So we come up with the formula:

<pre><code>x = (y + .3) / .971
</code></pre>

Which defines this infamous number, x. Also, it answers our question; What amount should I charge a card in order to cover the transaction fee and not fall short of the amount we want to take home? Well, all we need to do is fill in the take home amount, which is y:

<pre><code>x = (100 + .3) / .971
x = ~103.30
</code></pre>

I hope this helps clarify.

blocks|key|2313310|text|在C#中|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2313311|public+decimal+CalcFee()
{
++++//PayPal+Percentage+Fee+=+0.29%25,+Fix+Fee+=+0.3
++++var+sum+=+this.Items.Sum(c+=>+c.Price+*+c.Qty);+//Total+Items
++++return+Math.Round(Math.Round((sum+%2B+(decimal)0.3)+/+(decimal)0.971,+2)+-+sum,+2);
}|code-block|syntax|javascript|2313312|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In C#

<pre><code>public decimal CalcFee()
{
 //PayPal Percentage Fee = 0.29%, Fix Fee = 0.3
 var sum = this.Items.Sum(c =&gt; c.Price * c.Qty); //Total Items
 return Math.Round(Math.Round((sum + (decimal)0.3) / (decimal)0.971, 2) - sum, 2);
}
</code></pre>

blocks|key|674768|text|一个数学问题。100%25不是你想的那样：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|674769|674770|100%25%2B需要收取的固定费用|unordered-list-item|674771|100%25是实际获得100%25，我们应用的是three|674772|规则|674773|例如：|674774|+97.10+%25+=+$+30
++1.00+%25+=+$+30+/+97.1
100.00+%25+=+$+30+/+97.1+*+100
============================
100.00+%25+~+30,90|code-block|syntax|javascript|674775|现在我们需要添加固定费用：|674776|$+30,90+%2B++$+0.30|674777|这将导致所请求的$+31.20|offset|length|style|CODE|674778|那么，这在Code中意味着什么呢？|674779|//untested,+not+a+php+developer+anymore
function+requiredChargement($requiredPrice)
{
++++$requiredPercentage+=+100.0+-+2.9;
++++$fullVariableCost+=+$requiredPrice+/+requiredPercentage+*+100.0;
++++return+round($fullVariableCost+%2B+0.3,+2);
}|674780|entityMap^0|0|0|0|0|0|0|0|0|0|8|7|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|17|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|18|8|@]|9|@]|A|$]]|$1|F|3|G|5|E|7|19|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|1A|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1B|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1C|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1D|8|@]|9|@]|A|$]]|$1|S|3|T|5|N|7|1E|8|@]|9|@]|A|$O|P]]|$1|U|3|V|5|6|7|1F|8|@$W|1G|X|1H|Y|Z]]|9|@]|A|$]]|$1|10|3|11|5|6|7|1I|8|@]|9|@]|A|$]]|$1|12|3|13|5|N|7|1J|8|@]|9|@]|A|$O|P]]|$1|14|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]]|15|$]]

A math problem. 100 % is not what you think:

<ul>
<li>100 % + the fixed fee needs to be charged</li>
<li>100 % is actualy <code>97,1 % payout ($ 30) + 2,9 % fee</code></li>
<li>To get 100 %, we apply the rule of three</li>
</ul>

e.g.:

<pre><code> 97.10 % = $ 30
 1.00 % = $ 30 / 97.1
100.00 % = $ 30 / 97.1 * 100
============================
100.00 % ~ 30,90
</code></pre>

Now we need to add the fixed fee:

<pre><code>$ 30,90 + $ 0.30
</code></pre>

Which is resulting in the requested <code>$ 31.20</code>

So what does this mean in Code?

<pre><code>//untested, not a php developer anymore
function requiredChargement($requiredPrice)
{
 $requiredPercentage = 100.0 - 2.9;
 $fullVariableCost = $requiredPrice / requiredPercentage * 100.0;
 return round($fullVariableCost + 0.3, 2);
}
</code></pre>

Sounds like an easy question, I know. I am literally stumped.

Here are two websites that have made the simple calculator:

<a href="http://thefeecalculator.com" rel="noreferrer">http://thefeecalculator.com</a>

<a href="http://ppcalc.com" rel="noreferrer">http://ppcalc.com</a>

I'm needing to calculate these PayPal's fees in my PHP application.

Here's what I got, say we wanted to be paid $30 "even" for membership fees. This is the function I'm using to calculate what we should charge to make up for it using PayPal's calculations (also described on both of the sites above): 2.9% of the transaction + $0.30.

<pre><code>function memfees()
{
 $calc = round((30 * .029) + 30 + .30,2);
 return $calc;
}
</code></pre>

Test it here: <a href="http://matt.mw/junk/php/memfees.php" rel="noreferrer">http://matt.mw/junk/php/memfees.php</a>
As you can see, it says 31.17.
Both of the other websites say it should be 31.20.
If I try $130.00, mine calculates to $134.07 and both of theirs calculate to $134.19.

What am I doing wrong?

Why am I using a Round function? Percentages cause some decimals to go past the hundredths place, and PayPal generates an error if there is more then 2 digits after the decimal. I thought people normally round money, (e.g. $31.6342 will be $31.63) but if that is the case, what am I doing wrong in my function? The amount that is off is further if there are large payments. This leads me to believe that something is wrong with the percentage portion.

Could you offer some help on this?

Thank you for your time.

How do I calculate PayPal's fees (2.9% + .30) on a fixed number?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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听起来很简单，我知道。我真的被难住了。这里有两个制作了这个简单计算器的网站：我需要在我的PHP应用程序中计算这些贝宝的费用。这是我得到的，说我们想要30美元的“甚至”会员费。这是我用来计算我们应该收取多少钱来弥补它的函数，使用PayPal的计算(也在上面的两个网站上描述)：交易的2.9% +0.30美元。functio...

问如何在固定数量上计算贝宝的费用(2.9% + .30)？
EN

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问如何在固定数量上计算贝宝的费用(2.9% + .30)？EN