Edit: @potench preev.com is an inaccurate indicator of the BTC/RUB rate because it is basing its calculation "based on the USD Bitcoin price" per its footnote, so of course it will never show a big deviation from the BTC/USD rate. For the true rate you need to look at the real-time bid/ask spread on a BTC/RUB exchange such as btc-e.com which is why I linked to https://bitcoinwisdom.com/markets/btce/btcrur or you can also look at https://btc-e.com/exchange/btc_rur: bid/ask is 20855/21099 RUB as of 22:09 UTC, so the arbitrage opportunity is approximately 2000 RUB.
1 BTC is 22,810.00 RUB (1)
1 BTC is $330.80 (2)
$330.80 is 22,982.67 RUB (3)
Arbitrage of 172.67 RUB
3. https://www.google.com/webhp?sourceid=chrome-instant&ion=1&e...
Unless you've already established accounts at several different exchanges, you really shouldn't try anything based off of an HN comment. Please be careful not to deposit funds which are then frozen because your account is new. That type of thing. New accounts are subject to much scrutiny.
In particular, be very careful when your motive is greed (or "to seize an opportunity," to use a euphemism). Bitcoin isn't subject to regulation. Exchanges essentially play by their own rules. And when the world is going nuts, that means exchanges have the ability to do pretty much whatever they decide is the right choice. If they decide to temporarily halt withdraws, and you're caught up in that net, you could potentially lose a lot, even if it doesn't seem like it.
Try not to risk more than, say, 20% of whatever you can afford to lose. Even if you think you can afford to lose it, the reality of losing it might kick you in the stomach harder than you probably realize.
EDIT: Also, if you absolutely insist on taking crazy risks like this, here's a tip: estimate the transaction fees, and then double it. That gives you a margin of error. Your transaction fees are usually what eat up much of your potential profits in this kind of thing, so if you pretend like they're double, you can avoid making some extremely risky decisions.
In fact, I'm just going to urge you to avoid this altogether. It's not fun to be in a position of staring at a financial chart and willing it to go up, knowing that if it doesn't, you're screwed. It's also not fun to sell, thinking you're screwed, when in reality if you'd just waited a little bit longer you would've been fine. Or when you resent yourself for selling too early and "not making as much money as you could have." This kind of greedy standalone thing will wrap your emotions around a pole, and it's way too easy to convince yourself you're the kind of person that can handle it.
Also realize that even if you do profit off of this, you can't really credit yourself for being clever. You'd be fooling yourself. At best, you can simply feel lucky. So there's not much skill involved in this, beyond putting in a lot of time to research how things work, etc, and then hoping the world ends up obeying your mental model, which rarely happens anyway.
Poker is way more fun than this. Go do that.
