<p><code>263.95 [USD/BTC] / 233.56 [USD/BTC] * 1 [BTC] = 1.13 [BTC]</code>, i.e. for each BTC you sold at the higher price, you can rebuy 1.13 BTC at the lower price.</p>

<p>The underlying concept is explained on <a href="http://en.wikipedia.org/wiki/Cross-multiplication" rel="nofollow">Wikipedia: Cross-multiplication</a>.</p>

CC BY-SA 3.0
2015-01-29T22:28:58.497Z
2015-01-29T22:28:58.497Z
Murch
<p>Say I had 1 Bitcoin at the start of the trade yesterday</p>

<pre><code> @ 01-27 14:29
</code></pre>

<p>and the price was </p>

<pre><code> USD : 263.95872470902
</code></pre>

<p>So, I sold the whole Bitcoin at the average price</p>

<p>Then</p>

<pre><code> @ 01-29 10:57
</code></pre>

<p>I bought back as much Bitcoin as the new price would let me again at the average price of</p>

<pre><code> USD : 233.55771464647
</code></pre>

<p>The price data was taken from crypto-prices.com I just don't see how that could be worked out. I know how to use preev.com to calculate the 'current' value but I don't understand how I would calculate a previous value and work out the difference / or would be, pretend profit.</p>

CC BY-SA 3.0
2015-01-29T22:51:57.500Z
I'm voting to close this question as off-topic because this question is essentially about elementary math and as such not a good fit for a Bitcoin experts' question and answer site.
Murch
<exchange-rate><charts><trade>
How do I calculate a hypothetical trade?
8DK
# How do I calculate a hypothetical trade?

(Asked by: username_0 on 2015-01-29)

Say I had 1 Bitcoin at the start of the trade yesterday

```
 @ 01-27 14:29

```

and the price was

```
 USD : 263.95872470902

```

So, I sold the whole Bitcoin at the average price

Then

```
 @ 01-29 10:57

```

I bought back as much Bitcoin as the new price would let me again at the average price of

```
 USD : 233.55771464647

```

The price data was taken from crypto-prices.com I just don't see how that could be worked out. I know how to use preev.com to calculate the 'current' value but I don't understand how I would calculate a previous value and work out the difference / or would be, pretend profit.

**Tags:** exchange-rate, charts, trade

> **Comments:**
> **username_1**: I'm voting to close this question as off-topic because this question is essentially about elementary math and as such not a good fit for a Bitcoin experts' question and answer site.  

---

## 1 answers

### Answer by username_1 on 2015-01-29. Score: 1 | Accepted answer

`263.95 [USD/BTC] / 233.56 [USD/BTC] * 1 [BTC] = 1.13 [BTC]`, i.e. for each BTC you sold at the higher price, you can rebuy 1.13 BTC at the lower price.

The underlying concept is explained on [Wikipedia: Cross-multiplication](http://en.wikipedia.org/wiki/Cross-multiplication).


---

